Electrochemical cells, solid oxide electrolysis cells, cell stacks, hot modules, and gas production equipment

Abstract

The electrochemical cell (electrolysis cell) comprises a solid electrolyte layer, an air electrode laminated on the front side of the solid electrolyte layer, and a fuel electrode laminated on the back side of the solid electrolyte layer, the fuel electrode having a functional layer containing a Ni alloy and a conductive solid oxide, and the Ni alloy contained in the functional layer has an average particle size of 0.77 μm or more and 1.00 μm or less.

Description

[Technical Field]

[0001] The present invention relates to an electrochemical cell, a solid oxide electrolysis cell, a cell stack, a hot module, and a gas production device. [Background technology]

[0002] Conventionally, solid oxide electrochemical cells using solid oxide as an electrolyte have been known (see Patent Document 1). Solid oxide electrochemical cells are characterized by performing electrochemical reactions with high efficiency in high-temperature environments, and can be used as solid oxide electrolysis cells (SOECs) or solid oxide fuel cells (SOFCs). Solid oxide electrolysis cells are electrolysis devices that use electrical energy to decompose water vapor into hydrogen and oxygen. Solid oxide fuel cells are power generation devices that generate electrical energy through a chemical reaction between hydrogen and oxygen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-92459 Summary of the Invention [Problem to be solved by the invention]

[0004] The electrochemical cell can be configured to include a solid electrolyte layer, a fuel electrode layer laminated on one side of the solid electrolyte layer, and an air electrode layer laminated on the other side of the solid electrolyte layer. The fuel electrode layer can be configured to contain Ni (nickel) as an electrode catalyst and an oxide having ion conductivity (e.g., YSZ (yttria-stabilized zirconia)).

[0005] When an electrochemical cell containing Ni in the anode layer is operated for a long time under harsh operating conditions (high temperature, high humidity, high current), Ni migration and aggregation occurs within the anode layer. When Ni migrates or aggregates within the anode layer, the internal resistance of the anode layer increases and the three-phase interface (the boundary between the fuel gas, Ni, and electrolyte (YSZ)) that serves as the reaction field decreases. This reduces the electrical characteristics of the electrochemical cell, making it impossible to achieve the desired performance. Therefore, there is a need for an electrochemical cell with improved durability that can maintain the desired performance even when operated for a long time.

[0006] The present disclosure has an object to solve the above-mentioned problems, that is, one object of the present disclosure is to improve the durability of electrochemical cells. [Means for solving the problem]

[0007] The electrochemical cell according to the present disclosure comprises: a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and The fuel electrode is NiFe a functional layer containing an alloy and a conductive solid oxide; The functional layer NiFe The average grain size of the alloy is 0.779 μm or more and 1.00 μm or less, The aforementioned NiFe The average particle size of the alloy is smaller than the average particle size of the conductive solid oxide.

[0008] The functional layer of the electrochemical cell according to the present disclosure contains a Ni alloy and a conductive solid oxide. The metal element that forms the Ni alloy by bonding with Ni suppresses the migration and aggregation of Ni. However, when the average particle size of the Ni alloy is 0.779If the average particle size of the Ni alloy is less than 1.0 μm, the effect of the metal element in suppressing the migration and aggregation of Ni is low. On the other hand, if the average particle size of the Ni alloy exceeds 1.0 μm, the metal element promotes densification of the interior of the fuel electrode layer during molding (sintering) of the fuel electrode layer, which reduces the gas diffusibility in the fuel electrode layer and, as a result, reduces the initial performance. If the average particle size of the Ni alloy contained in the functional layer is 0.779 When the particle size is from 1.00 μm to 1.00 μm, the durability of the electrochemical cell can be improved while suppressing a decrease in the initial performance. The Ni alloy is a NiFe alloy. Fe has the property of effectively suppressing the migration and aggregation of Ni by forming a NiFe alloy. Therefore, when the Ni alloy is a NiFe alloy, it is possible to suppress the deterioration of the initial performance of the electrochemical cell while enhancing the effect of improving durability. Furthermore, one cause of deterioration of the functional layer of the fuel electrode layer is the disconnection of the conduction path (pathway of ion conduction) in the conductive solid oxide. The larger the average particle size of the conductive solid oxide, the less likely the conduction path in the conductive solid oxide is to be disconnected, and therefore the more difficult the deterioration progresses. Therefore, when the relationship between the average particle size of the Ni alloy and the average particle size of the conductive solid oxide is specified as described above, the conduction path in the conductive solid oxide is stabilized. Therefore, the effect of improving durability can be enhanced. In addition, when the fuel electrode layer contains a metal element other than Ni, particles of elemental Ni may be present in the functional layer in addition to particles of an alloy of Ni and the metal. Therefore, in the present disclosure, the average particle size of the Ni alloy may also be the "average particle size of the Ni alloy and elemental Ni."

[0010] A pore size ratio, which is the ratio of the average particle size of the conductive solid oxide to the average size of the pores contained in the functional layer, may be 1.5 or more and 2.6 or less. If the average diameter of the pores contained in the functional layer is too small, the functional layer will be dense, resulting in low gas diffusibility in the functional layer. This will result in a decrease in the initial performance of the electrochemical cell. Furthermore, if the average diameter of the pores contained in the functional layer is too large, Ni will be more likely to migrate and aggregate, resulting in a decrease in durability. Therefore, a pore diameter ratio of 1.5 or more and 2.6 or less can enhance the effect of improving durability while suppressing a decrease in the initial performance of the electrochemical cell.

[0011] The electrochemical cell according to the present disclosure comprises: a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and The fuel electrode is NiFe a functional layer containing an alloy and a conductive solid oxide; The functional layer NiFe The average grain size of the alloy is 0.779 μm or more and 1.00 μm or less, The pore size ratio, which is the ratio of the average particle size of the conductive solid oxide to the average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less. The functional layer of the electrochemical cell according to the present disclosure contains a Ni alloy and a conductive solid oxide, and the metal element that bonds with Ni to form a Ni alloy suppresses the migration and aggregation of Ni. The Ni alloy is a NiFe alloy. Fe has the property of effectively suppressing the migration and aggregation of Ni by forming a NiFe alloy. Therefore, when the Ni alloy is a NiFe alloy, it is possible to suppress the deterioration of the initial performance of the electrochemical cell while enhancing the effect of improving durability. However, the average grain size of the Ni alloy is 0.779 If the average particle size of the Ni alloy is less than 1.0 μm, the effect of the metal element in suppressing the migration and aggregation of Ni is low. On the other hand, if the average particle size of the Ni alloy exceeds 1.0 μm, the metal element promotes densification of the interior of the fuel electrode layer during molding (sintering) of the fuel electrode layer, which reduces the gas diffusibility in the fuel electrode layer and, as a result, reduces the initial performance. If the average particle size of the Ni alloy contained in the functional layer is 0.779 When the particle size is from 1.00 μm to 1.00 μm, the durability of the electrochemical cell can be improved while suppressing a decrease in the initial performance. Furthermore, when the pore diameter ratio is 1.5 or more and 2.6 or less, the effect of improving durability while suppressing a decrease in the initial performance of the electrochemical cell can be enhanced.

[0013] The average particle size of the Ni alloy may be smaller than the average particle size of the conductive solid oxide. When the relationship between the average particle size of the Ni alloy and the average particle size of the conductive solid oxide is specified as described above, the conductive paths in the conductive solid oxide are stabilized, thereby enhancing the effect of improving durability.

[0016] A solid oxide electrolysis cell according to the present disclosure comprises an electrochemical cell according to the present disclosure.

[0017] Such a configuration makes it possible to provide a solid oxide electrolysis cell that is improved in durability while suppressing deterioration in initial performance.

[0018] The cell stack according to the present disclosure is formed by stacking a plurality of solid oxide electrolysis cells according to the present disclosure.

[0019] With this configuration, it is possible to provide a cell stack that has improved durability while suppressing deterioration in initial performance.

[0020] The hot module according to the present disclosure includes: a cell stack according to the present disclosure; a vaporizer that generates water vapor to be supplied to the cell stack; a heat exchanger that exchanges heat with the gas supplied to the cell stack; a heater for heating the cell stack; a heat insulating material in which the cell stack, the vaporizer, the heat exchanger, and the heater are disposed; Equipped with.

[0021] With this configuration, a hot module with improved durability can be provided.

[0022] The gas production apparatus according to the present disclosure includes the hot module according to the present disclosure.

[0023] With this configuration, it is possible to provide a gas production device with improved durability. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram of a hydrogen production device equipped with a hot module. [Figure 2] FIG. 2 is a perspective view of a cell stack of a solid oxide electrolysis cell (SOEC) according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line II-II in FIG. [Figure 4] FIG. 4 is a cross-sectional view in the thickness direction of a single cell included in the electrolysis unit of FIG. 1 . [Figure 5] FIG. 5 is a graph showing the relationship between the average particle size of the NiFe alloy and the durability deterioration rate. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a block diagram of a hydrogen production device 1 according to this embodiment. The hydrogen production device 1 according to this embodiment is a device that produces hydrogen from water vapor. The hydrogen production device 1 according to this embodiment is an example of a gas production device of the present invention. As shown in FIG. 1, the hydrogen production device 1 includes a hot module 10 and a condenser 90.

[0026] The hot module 10 is constructed by covering with insulating material the main components that become hot among the elements that make up the hydrogen production device 1, and is a device in which the main components are concentrated within the insulating material so that they can be kept at a high temperature. This hot module 10 includes a cell stack 20, a vaporizer 30, a heat exchanger 40, a heater 50, and insulating material 60.

[0027] 1, water (H2O) is supplied to the vaporizer 30. The vaporizer 30 is configured to heat the supplied water to a temperature of 100°C or higher by a heat source (not shown). Therefore, the water supplied to the vaporizer 30 evaporates within the vaporizer 30, generating water vapor. The water vapor generated in the vaporizer 30 is introduced into the heat exchanger 40.

[0028] In addition to the water vapor described above, air is introduced into the heat exchanger 40. High-temperature hydrogen (H2) and high-temperature oxygen (O2) generated in the cell stack 20, which will be described later, are also introduced into the heat exchanger 40. These high-temperature gases exchange heat with the water vapor and air in the heat exchanger 40, thereby heating the water vapor and air introduced from the vaporizer 30 in the heat exchanger 40.

[0029] The water vapor and air heated by the heat exchanger 40 are further heated by the heater 50 to the operating temperature of the cell stack 20 (i.e., the temperature required to operate the cell stack 20).The water vapor and air are then introduced into the cell stack 20.

[0030] The cell stack 20 is formed by stacking solid oxide electrolysis cells. The cell stack 20 is heated to an operating temperature by a heat source (such as a burner) not shown. A predetermined voltage is applied to the cell stack 20. As a result, water vapor introduced into the cell stack 20 is electrolyzed to produce hydrogen and oxygen. The hydrogen produced in the cell stack 20 is introduced into the heat exchanger 40 together with unreacted water vapor, where it is used to heat the water vapor and air, and then introduced into the condenser 90. The unreacted water vapor is condensed in the condenser 90. The water condensed in the condenser 90 is introduced into the vaporizer 30. Meanwhile, the hydrogen separated by the condensation of the water vapor in the condenser 90 is recovered. The oxygen produced in the cell stack 20 is introduced into the heat exchanger 40, where it is used to heat the water vapor and air, and then introduced into the vaporizer 30 to heat the water supplied to the vaporizer 30. The oxygen discharged from the vaporizer 30 is recovered (or released into the atmosphere).

[0031] The cell stack 20, vaporizer 30, heat exchanger 40, and heater 50 are disposed inside the thermal insulation material 60. This suppresses heat radiation from the cell stack 20, vaporizer 30, heat exchanger 40, and heater 50 to the outside of the thermal insulation material 60. Heat-resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), and / or a heat-resistant container formed from these heat-resistant fibers, may be used for the thermal insulation material 60. The heat-resistant fibers are disposed so as to fill gaps between the cell stack 20, vaporizer 30, heat exchanger 40, and heater 50.

[0032] FIG. 2 is a perspective view of the cell stack 20, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 . As shown in FIGS. 2 and 3 , the cell stack 20 comprises an electrolysis unit group including a plurality of rectangular flat-plate-shaped electrolysis units Ue stacked in the thickness direction (vertical direction), and a pair of end plates 27, 28 disposed on the upper and lower surfaces of the electrolysis unit group, respectively. The end plates 27, 28 are each a rectangular flat-plate-shaped member having the same outer shape as the electrolysis unit Ue, and each have a rectangular opening formed in their center. The electrolysis unit group and the end plates 27, 28 are fastened to each other at their four corners by bolts B inserted through the end plates 27, 28 in the thickness direction and nuts (not shown). The end plates 27, 28 are made of metal (for example, stainless steel) and function as an anode and a cathode, respectively, when a voltage is applied. For ease of explanation, the proportions of the components in the drawings may differ from the actual proportions.

[0033] The electrolysis unit Ue will be described with reference to Fig. 3. As shown in Fig. 3, the electrolysis unit Ue comprises a solid oxide electrolysis cell 21 (hereinafter sometimes simply referred to as the electrolysis cell 21), an interconnector 22, a separator 23, a cathode frame 24, a fuel electrode frame 25, and a current collector 26.

[0034] The electrolysis cell 21 is an example of an electrochemical cell of the present invention. The electrolysis cell 21 is the smallest unit of an SOEC and includes a solid electrolyte layer 211, an air electrode layer 212 laminated on its upper surface, and an anode layer 213 laminated on its back surface. The air electrode layer 212 has a smaller outer shape than the solid electrolyte layer 211 and the anode layer 213, and is disposed in the center of the upper surface of the solid electrolyte layer 211 when viewed from above. Therefore, the upper surface of the outer periphery of the solid electrolyte layer 211 is exposed to the outside.

[0035] The interconnector 22 is a rectangular metal (for example, stainless steel) member that has a rectangular current collecting part 22a that protrudes downward from the centre of its lower surface. A pair of interconnectors 22 is arranged on both sides of the electrolysis cell 21 in the thickness direction. Two adjacent electrolysis units Ue share one interconnector 22. The interconnector 22 also functions as a separator that separates the two adjacent electrolysis units Ue. The lower surface of the current collecting part 22a is in contact with the upper surface of the air cathode layer 212 of the electrolysis cell 21. The lower electrolysis unit Ue includes a pair of interconnectors 22, 29 instead of the pair of interconnectors 22, 22. The interconnector 29 is arranged at the bottom end of the cell stack 20 and differs from the other interconnectors 22 in that it does not have a current collecting part 22a.

[0036] The separator 23 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in the center. The periphery of the opening of the separator 23 is brazed to the upper surface of the outer periphery of the solid electrolyte layer 211 of the electrolysis cell 21 with a brazing material (e.g., Ag brazing) (not shown). The separator 23 prevents mixing of oxygen generated in the air electrode layer 212 by electrolysis of water vapor and hydrogen generated in the fuel electrode layer 213.

[0037] The cathode frame 24 is a rectangular plate-shaped insulating member and may be formed of, for example, a mica sheet. A rectangular opening is formed in the center of the cathode frame 24. The cathode frame 24 is disposed between the separator 23 and the interconnector 22 above it.

[0038] The fuel electrode frame 25 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in the center thereof. The fuel electrode frame 25 is disposed between the separator 23 and the interconnector 22 below it.

[0039] The internal space of the electrolysis unit Ue is partitioned by the separator 23 into an air chamber Sa and a fuel chamber Sf. The air chamber Sa is a space that allows the flow of oxygen generated in the air electrode layer 212, and is defined by a space surrounded by the upper interconnector 22, separator 23, air electrode frame 24, and electrolysis cell 21. The fuel chamber Sf is a space that allows the flow of hydrogen generated in the fuel electrode layer 213, and is defined by a space surrounded by the lower interconnector 22, separator 23, fuel electrode frame 25, and electrolysis cell 21.

[0040] The current collector 26 is a rectangular porous member made of metal (for example, nickel) that is smaller than the fuel electrode layer 213 in plan view and allows hydrogen to pass through. The current collector 26 is arranged in the fuel chamber Sf so as to be in contact with the lower surface of the fuel electrode layer 213 and the upper surface of the lower interconnector 22. Two adjacent electrolysis cells 21 are stacked in the thickness direction so as to share the interconnector 22 via the current collector 26, thereby electrically connecting the multiple electrolysis cells 21 in series.

[0041] 2 and 3, four paths Pfi, Pfo, Pai, and Pao are formed as gas flow paths around the outer periphery of the cell stack 20. These paths Pfi, Pfo, Pai, and Pao are each formed to penetrate through members of the cell stack 20 in the thickness direction, excluding the "end plate 27" and the "upper interconnector 22 of the upper electrolysis unit Ue."

[0042] The path Pfi is formed near one corner of side E1, which is one of the four sides that make up the outer periphery of the cell stack 20. The path Pfo is formed near the other corner of side E2 that faces side E1 (the corner located diagonally from the one corner of side E1). As shown in FIG. 3 , the path Pfi communicates with the fuel chamber Sf via a horizontal hole 25a formed in the anode frame 25 of each electrolysis unit Ue. The path Pfo communicates with the fuel chamber Sf via a horizontal hole 25b formed in the anode frame 25 of each electrolysis unit Ue.

[0043] The path Pai is formed near one corner of the side E2. The path Pao is formed near the other corner of the side E1. The path Pai and the path Pao each communicate with the air chamber Sa via a horizontal hole (not shown) formed in the air electrode frame 24 of each electrolysis unit Ue.

[0044] Next, the configuration of the electrolysis cell 21 will be described in more detail with reference to FIG. 4. FIG. 4 is a cross-sectional view of the electrolysis cell 21 in the thickness direction. As described above, the electrolysis cell 21 includes a solid electrolyte layer 211, an air electrode layer 212, and an anode layer 213. In this embodiment, the solid electrolyte layer 211 is a rectangular flat layer measuring 150 mm square and 6 μm thick, and is configured to contain YSZ (yttria-stabilized zirconia). The solid electrolyte layer 211 has high oxide ion conductivity. The solid electrolyte layer 211 is a dense layer designed to prevent leakage between the air atmosphere at the air electrode and the reducing atmosphere at the anode. The solid electrolyte layer 211 is formed by sintering.

[0045] The air electrode layer 212 is laminated on the upper surface 211B (other surface) of the solid electrolyte layer 211. The air electrode layer 212 is a rectangular flat layer with a thickness of 108 μm, is configured to contain a perovskite oxide such as LSCF (lanthanum strontium cobalt iron oxide), and is formed by sintering. The air electrode layer 212 has a functional layer and a current collecting layer. The current collecting layer is thicker than the functional layer and is disposed on the upper surface of the functional layer. The air electrode layer 212 has high electronic conductivity and effectively collects electrons from the current collecting layer. The air electrode layer 212 is a porous layer with pores inside.

[0046] The anode layer 213 is a rectangular flat layer measuring 150 mm on each side, and is formed to be thicker than the solid electrolyte layer 211 and the air cathode layer 212, for example, approximately 400 μm. The thick anode layer 213 supports the solid electrolyte layer 211 and the air cathode layer 212. In other words, the electrolysis cell 21 is an anode-supported cell. The anode layer 213 has a functional layer 213 a and a support layer 213 b. The support layer 213 b is formed to be significantly thicker than the functional layer 213 a, and the thickness ratio can be set to be approximately 16 to 40 times.

[0047] The fuel electrode layer 213 is laminated on the back surface 211A (one side), which is the bottom surface in FIG. 4, of the solid electrolyte layer 211. Specifically, the functional layer 213a of the fuel electrode layer 213 is laminated on the back surface 211A of the solid electrolyte layer 211, and the support layer 213b is laminated on the back surface (bottom surface in FIG. 4) of the functional layer 213a. In other words, the functional layer 213a and the support layer 213b are laminated on the back surface 211A of the solid electrolyte layer 211 in this order. The fuel electrode layer 213 is also formed by sintering.

[0048] The main component of the support layer 213b is a cermet of Ni (nickel) and YSZ. The support layer 213b is configured to be porous, including a plurality of micropores (not shown). The diameter of the micropores is on the order of several μm, which ensures the permeability of water vapor. The main component of the functional layer 213a is also a cermet of Ni and YSZ. Like the support layer 213b, the functional layer 213a is also configured to be porous, including a plurality of micropores (not shown), but is denser than the support layer 213b. In other words, the porosity of the functional layer 213a is smaller than the porosity of the support layer 213b.

[0049] The operation of the cell stack 20 will be described. First, a voltage is applied between the end plates 27, 28 of the cell stack 20. Next, high-temperature steam is supplied from the path Pfi. The steam supplied to the path Pfi flows into the fuel chamber Sf of each electrolysis unit Ue via the horizontal holes 25a. In addition, high-temperature air is supplied from the path Pai. The air supplied to the path Pai flows into the air chamber Sa of each electrolysis unit Ue via horizontal holes (not shown). The reason for supplying high-temperature air to the air chamber Sa is to control the temperature of the cell stack 20.

[0050] The water vapor that flows into the fuel chamber Sf passes through the support layer 213b of the fuel electrode layer 213 and moves to the functional layer 213a. In the functional layer 213a, the water vapor reacts with electrons supplied from the end plate 28 via the current collector 26 and is decomposed into hydrogen and oxide ions (water electrolysis reaction). The hydrogen diffuses within the fuel chamber Sf, is discharged through the horizontal hole 25b via path Pfo, and is recovered by a well-known method. At this time, unreacted water vapor can be discharged along with the hydrogen via path Pfo. Meanwhile, the oxide ions move through the solid electrolyte layer 211 to the air electrode layer 212 in the air chamber Sa, release electrons in the functional layer of the air electrode layer 212, and become oxygen. The oxygen diffuses within the air chamber Sa, and is discharged through path Pao via a horizontal hole (not shown) together with the air that flowed into the air chamber Sa, and is recovered (or released to the atmosphere) by a well-known method. Electrons emitted from the functional layer of the air electrode layer 212 are collected by the current collecting portion 22a of the interconnector 22 via the current collecting layer, and circulate from the end plate 27 to the end plate 28 via the external power supply.

[0051] The cell stack 20 operates as described above, and hydrogen is produced in the hydrogen production device 1.

[0052] It has been confirmed that, when the cell stack 20 operates for a long time, Ni in the fuel electrode layer 213 migrates and aggregates within the fuel electrode layer 213. When Ni migrates and aggregates within the fuel electrode layer 213, the Ni concentration near the interface between the functional layer 213a and the solid electrolyte layer 211 decreases, and the reaction efficiency of the water electrolysis reaction decreases. Furthermore, when Ni migrates and aggregates within the fuel electrode layer 213, the conduction path (pathway for ion conduction) within the fuel electrode layer 213 decreases, and the internal resistance increases. This decrease in reaction efficiency and increase in internal resistance deteriorates the fuel electrode layer 213.

[0053] In the present disclosure, durability is improved by alloying Ni with other metal elements (Ni alloying) in the functional layer 213a of the fuel electrode layer 213 and specifying the average particle size of this alloy within a predetermined range. Furthermore, by making the average particle size of the Ni alloy smaller than the average particle size of the YSZ in the functional layer 213a, the effect of improving durability can be enhanced while suppressing a decrease in initial performance. Furthermore, by setting the pore size ratio, which is the ratio of the average particle size of the YSZ in the functional layer 213a to the average diameter of the pores contained in the functional layer 213a, within a predetermined range, the effect of improving durability can be enhanced while suppressing a decrease in initial performance.

[0054] (Ni alloy) In the present disclosure, a NiFe alloy is used as the Ni alloy. When Fe (iron) is contained in the fuel electrode layer 213, the progression of deterioration of the fuel electrode layer 213 can be suppressed. Fe also serves as a sintering aid, and can improve the sinterability of YSZ and Ni when manufacturing the fuel electrode layer 213. However, the metal element added to the fuel electrode layer 213 to generate the Ni alloy is not limited to Fe.

[0055] (Average particle size of Ni alloy) 5 is a graph showing the relationship between the average particle size of NiFe alloy particles and the durability degradation rate. The average particle size was measured as follows. First, the functional layer 213a was cut along a plane along the thickness direction of the fuel electrode layer 213 (the thickness direction of the electrolysis cell 21), and the cut surface was photographed using a scanning electron microscope (SEM). The resulting SEM image was then tri-leveled into white, black, and gray. This resulted in an SEM image in which YSZ was white, pores were black, and the metal was gray. The gray areas in the tri-leveled SEM image were then considered to be particles of the NiFe alloy, and the average particle size in the gray areas of the tri-leveled SEM image was measured using the intercept method.

[0056] In the ternary SEM image, it is impossible to distinguish whether the gray area is a NiFe alloy, pure Ni, or pure Fe. However, since almost all of the Ni and Fe contained in the functional layer 213a can be considered to be alloyed, the average particle size of the gray area in the SEM image was considered to be the average particle size of the NiFe alloy. If the total volume of Fe in the functional layer 213a is smaller than the total volume of Ni, there is a possibility that pure Ni not alloyed with Fe is present. Therefore, if pure Ni is present, the average particle size of the NiFe alloy may be the “average particle size of the NiFe alloy and pure Ni.” The “average particle size of the NiFe alloy” can also be considered the “average particle size of the metal particles present in the fuel electrode layer 213 obtained by sintering a material in which a small amount (specifically, a smaller volume than Ni) of Fe (i.e., a metal element other than Ni) is added to Ni and YSZ, a conductive solid oxide.”

[0057] However, when the inventors measured the average particle size of metal particles present in the fuel electrode layer obtained by sintering a material consisting of Ni and YSZ (a conductive solid oxide) without Fe addition and the average particle size of metal particles present in the fuel electrode layer obtained by sintering a material consisting of Ni and YSZ (a conductive solid oxide) with Fe addition, they found that the metal particles in the fuel electrode layer consisting of the material consisting of Fe-added material were larger in size than the metal particles in the fuel electrode layer consisting of the material consisting of Fe-free material, and no particles with a size similar to that of the metal particles in the fuel electrode layer consisting of the material consisting of Fe-free material were found. This is thought to be because when the material consisting of Fe was added was sintered, all of the Ni and Fe were alloyed with NiFe, and the NiFe alloy particles grew. Therefore, it is thought that the metal particles present in the fuel electrode layer obtained by sintering a material consisting of Ni and YSZ (a conductive solid oxide) with a small amount of Fe addition are almost entirely NiFe alloy particles.

[0058] Whether the metal particles contained in the functional layer 213a are particles of simple Ni or particles of a NiFe alloy can be analyzed by X-ray diffraction (XRD). Specifically, if the metal particles contained in the functional layer 213a are particles of simple Ni, a peak derived from Ni appears in the diffraction profile (diffraction pattern) obtained by X-ray diffraction. Similarly, if the metal particles contained in the functional layer 213a are particles of a NiFe alloy, a peak derived from the NiFe alloy appears in the diffraction profile. The peak derived from the NiFe alloy appears at a position shifted by a predetermined angle (e.g., 0.02° or more) from the peak derived from simple Ni. Therefore, by identifying the angle at which the peak appears, it is possible to analyze whether the metal particles contained in the functional layer 213a are particles of simple Ni or particles of a NiFe alloy. In addition, whether the metal particles appearing in a cross section of the functional layer 213a are particles of simple Ni or particles of a NiFe alloy can also be analyzed (identified) using an electron probe microanalyzer (EPMA).

[0059] The durability deterioration rate is Durability degradation rate = (((Voltage after 1000 hours) - (Initial voltage)) / (Initial voltage)) x 100 [%] The "initial voltage" is the "voltage applied to pass a predetermined current through the electrolytic cell," and the "voltage after 1000 hours" is the "voltage applied to pass the predetermined current through the electrolytic cell after the predetermined current has been passed through the electrolytic cell for 1000 hours." As the internal resistance of an electrolytic cell increases with deterioration, the "voltage applied to pass a predetermined current through the electrolytic cell" increases with continued use. Therefore, the smaller the value of the durability deterioration rate, the smaller the deterioration and the higher the durability.

[0060] As shown in Figure 5, when the average particle size of the NiFe alloy is in the range of 0.779 to 1.00 μm, the durability degradation rate is in the range of 5.7 to 7.5%. In contrast, when the average particle size of the NiFe alloy is less than 0.779 μm or more than 1.00 μm, the durability degradation rate is 15% or more. Thus, when the average particle size of the NiFe alloy is in the range of 0.779 to 1.00 μm, durability is high. For this reason, the average particle size of the NiFe alloy is set in the range of 0.77 to 1.00 μm.

[0061] Here, it was confirmed that there is a positive correlation between the "volume fraction of Fe relative to the total volume of Ni and Fe in the functional layer 213a" (hereinafter referred to as the Fe volume fraction) and the average particle size of the NiFe alloy. Therefore, by specifying the Fe volume fraction, the average particle size of the NiFe alloy can be controlled within the range of this embodiment, i.e., 0.779 to 1.00 μm.

[0062] (Relationship between the average grain size of Ni alloy and that of YSZ) In the present disclosure, assuming that the average particle size of the NiFe alloy is in the range of 0.779 μm to 1.00 μm, it is preferable that the average particle size of YSZ be larger than that of the NiFe alloy. One cause of deterioration of the functional layer 213a of the fuel electrode layer 213 is the disconnection of the YSZ conductive paths during use. A small average particle size of YSZ makes the conductive paths more likely to be disconnected during use, leading to accelerated deterioration. Conversely, a larger average particle size of YSZ makes the conductive paths less likely to be disconnected, leading to less degradation. Therefore, to improve the durability of the functional layer 213a, a large average particle size of YSZ is preferable. The average particle size of YSZ can be measured using the same method as that for the NiFe alloy. Specifically, the white area in a ternary-valued SEM image of the cross section of the functional layer 213a is considered to be YSZ, and the average particle size of the gray area in the ternary-valued SEM image can be measured using the intercept method.

[0063] The relationship between the average grain size of YSZ and the average grain size of NiFe alloy in the functional layer 213a is affected by the grain size of the YSZ starting material. Specifically, if the grain size of the YSZ starting material is small, the average grain size of YSZ will be smaller than the average grain size of NiFe alloy. In this case, as mentioned above, the conductive paths are more likely to be broken, resulting in reduced durability. Furthermore, if the volume fraction of Fe is small and the average grain size of NiFe alloy is larger than the average grain size of YSZ, the effect of Fe as a sintering aid is reduced. If the grain size of the YSZ starting material is large, the average grain size of YSZ will be larger than the average grain size of NiFe alloy. However, if the volume fraction of Fe is too large, the average grain size of NiFe alloy will be larger than the average grain size of YSZ. This is thought to be because the presence of Fe between YSZ particles inhibits the growth of YSZ particles due to bonding between YSZ particles.

[0064] Specifically, by making the particle size of the YSZ starting material smaller than that of the NiFe precursor starting material, the average particle size of the YSZ in the functional layer 213a can be made smaller than that of the NiFe alloy. Conversely, by making the particle size of the YSZ starting material larger than that of the NiFe precursor starting material, the average particle size of the YSZ in the functional layer 213a can be made larger than that of the NiFe alloy.

[0065] (pore diameter ratio) The pore size ratio of the functional layer 213a is 1.5 or more and 2.6 or less. The pore size ratio is the ratio of the average particle size of the YSZ to the average size of the pores contained in the functional layer 213a. Pore ​​diameter ratio=(average particle diameter of YSZ contained in functional layer 213a) / (average diameter of pores contained in functional layer 213a) The pore diameter ratio is calculated as follows. When the pore diameter ratio is small, i.e., when the average pore diameter is large, YSZ tends to become brittle. On the other hand, when the pore diameter ratio is large, i.e., when the average pore diameter is small, Ni mobility becomes difficult, improving durability. On the other hand, when the average pore diameter is small, gas diffusibility in the functional layer 213a decreases, resulting in a decrease in initial performance. In the present disclosure, by setting the pore diameter ratio to 1.5 or more and 2.6 or less, durability can be improved while maintaining (or preventing a decrease in) initial performance. Furthermore, by setting the pore diameter ratio within this range, embrittlement of YSZ can be prevented. The average pore diameter can be measured using a method similar to that for measuring the average particle diameter of a NiFe alloy. That is, in an SEM image of a cross section of the ternary-valued functional layer 213a, the black areas are considered to be pores, and the average diameter of the black areas calculated using the intercept method can be used as the average pore diameter.

[0066] (Example) 1. Sample Preparation NiO powder and Fe2O3 powder were mixed in a predetermined ratio and stirred for a predetermined time using a ball mill or the like. The mixture was then washed with alcohol, and the liquid mixture was placed in a bowl. The alcohol was evaporated in the bowl to dry the mixture and form it into a powder. The powder was calcined at approximately 800°C. This produced a composite oxide powder containing Ni and Fe (NiFe precursor powder). The produced composite oxide powder and YSZ powder were mixed in a predetermined ratio and stirred for a predetermined time using a ball mill or the like. Next, butyral resin, polyvinyl acetal resin (G-260, Sekisui Chemical Co., Ltd.) as a plasticizer, a known dispersant, a mixed solvent of toluene and ethanol, and optionally a pore-forming agent (typically organic beads) were added to the mixed powder in predetermined ratios and mixed in a ball mill to prepare a slurry. The slurry was then formed into a green sheet of the functional layer of the fuel electrode layer having a predetermined thickness using a doctor blade method. This green sheet is sintered to form a functional layer of the fuel electrode layer in which the NiFe alloy is uniformly dispersed.

[0067] NiO powder and YSZ powder were mixed in a predetermined ratio and stirred for a predetermined time using a ball mill or the like. Next, butyral resin, polyvinyl acetal resin as a plasticizer, a known dispersant, a mixed solvent of toluene and ethanol, and optionally a pore-forming agent (typically organic beads) were added to the mixed powder in predetermined ratios and mixed in a ball mill to prepare a slurry. Then, a green sheet of the support layer for the fuel electrode layer having a predetermined thickness was formed from the slurry using a doctor blade method. This green sheet was sintered to form the support layer for the fuel electrode layer.

[0068] In addition, butyral resin, polyvinyl acetal resin as a plasticizer, a known dispersant, and a mixed solvent of toluene and ethanol were added to the YSZ powder in predetermined proportions and mixed in a ball mill to prepare a slurry. A doctor blade method was then used to form a green sheet of a solid electrolyte layer having a predetermined thickness from the slurry. The green sheet was sintered to form the solid electrolyte layer.

[0069] Next, a green sheet for the functional layer of the fuel electrode layer and a green sheet for the support layer of the fuel electrode layer were stacked in this order on one side of the green sheet for the solid electrolyte layer. These stacked green sheets were then pressed together under high pressure using a press while being heated and evacuated. This formed a laminate including the green sheet for the solid electrolyte layer, the green sheet for the functional layer of the fuel electrode layer, and the green sheet for the support layer of the fuel electrode layer.

[0070] The laminate formed as described above was then degreased at a predetermined temperature (e.g., 200 to 300°C). The laminate was then fired (primary firing) at a predetermined first temperature (e.g., 1300 to 1400°C) for a predetermined time (e.g., 1 to 5 hours). This resulted in the formation of a primary sintered body having a solid electrolyte layer and a fuel electrode layer stacked on one side of the solid electrolyte layer.

[0071] Next, a material containing LSCF was screen-printed on the other side of the solid electrolyte layer of the formed primary sintered body, and the resulting product was fired at a predetermined second temperature (e.g., 900 to 1000°C) for a predetermined time (e.g., 1 to 5 hours) (secondary firing). This produced a sample electrolysis cell comprising a solid electrolyte layer, a fuel electrode layer laminated on one side of the solid electrolyte layer, and a cathode layer laminated on the other side of the solid electrolyte layer.

[0072] Furthermore, when forming the green sheet for the functional layer of the fuel electrode layer, the average particle size of the NiFe alloy contained in the formed fuel electrode layer can be changed by changing the volume fraction (compounding ratio) of Fe. By setting the volume fraction of Fe in the range of 5.0 to 20.0%, these can be within the range of this embodiment. Therefore, by changing the volume fraction of Fe in the range of 5.0 to 20.0%, example samples with different average particle sizes of the NiFe alloy contained in the fuel electrode layer were created. Furthermore, by changing the volume fraction of Fe outside the range of 5.0 to 20.0%, comparative example samples were created.

[0073] Furthermore, by changing the particle size of the YSZ mixed during molding of the green sheet for the functional layer of the fuel electrode layer, it is possible to change the relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ. o C, the pore size ratio can be changed by changing the time between 1 and 5 hours. Therefore, by changing the particle size of the YSZ to be mixed and the primary firing conditions, we created several example samples with different pore size ratios and different size relationships between the average particle size of the NiFe alloy contained in the anode and the average particle size of the YSZ.

[0074] 2. Measurement of average grain size of NiFe alloy Each sample was cut along the thickness direction of the anode layer (cell thickness direction), and the cut surface was photographed using an SEM. The resulting SEM image was tri-leveled into white, black, and gray. The gray area was considered to be the NiFe alloy area, and the average grain size of the NiFe alloy was measured using the intercept method. The white area was considered to be the YSZ area, and the average grain size of the YSZ was measured using the intercept method. The black area was considered to be the pore area, and the average pore diameter was measured using the intercept method.

[0075] 3. Measurement of initial performance and durability deterioration rate The current per unit area (current density) was measured when a constant voltage (1 to 1.3 V) was applied between the fuel electrode layer and the air electrode layer of each sample. The measured current density was used as an evaluation index for initial performance. The higher the current density, the better the initial performance. A voltage was applied between the fuel electrode layer and the air electrode layer of each sample so that a constant current flowed through each sample. The applied voltage increased over time due to an increase in the internal resistance within the sample. The difference between the voltage applied initially and the voltage applied after a predetermined time (e.g., 400 hours) was calculated, and this calculated value was converted to the difference between the voltage that would be applied after 1,000 hours. The converted value was then divided by the initially applied voltage to calculate the durability degradation rate as a percentage. A smaller durability degradation rate indicates higher durability.

[0076] 4.Measurement results Table 1 shows the initial performance (current density) measured and its evaluation, the durability deterioration rate and its evaluation, and an overall evaluation for the samples of each example and each comparative example.

[0077] [Table 1]

[0078] In Table 1, when the durability degradation rate was less than 8%, the durability was evaluated as very good (◎), when the durability degradation rate was 8% or more but less than 12%, the durability was evaluated as good (◎), when the durability degradation rate was 12% or more but less than 15%, the durability was evaluated as fairly good (○), and when the durability degradation rate was 15% or more, the durability was evaluated as poor (×). 2 When the current density was 1.0 mA / cm or more, the initial performance was evaluated as good (○). 2 If the evaluation result of durability was less than 1 / 3, the initial performance was evaluated as poor (×). If the evaluation result of durability was very good (◎◎) and the evaluation result of initial performance was good (○), the overall judgment was judged to be very good (◎◎). If the evaluation result of durability was good (◎) and the evaluation result of initial performance was good (○), the overall judgment was judged to be good (◎). If the evaluation result of durability was fairly good (○) and the evaluation result of initial performance was good (○), the overall judgment was judged to be fairly good (○). Furthermore, if the evaluation result of durability was poor (×), the overall judgment was judged to be poor (×) regardless of the evaluation result of initial performance.

[0079] (Grain size of NiFe alloy) As can be seen from Table 1, the overall evaluations for all Examples 1 to 18 were fairly good (◯), good (◎), and very good (◎◎). On the other hand, Comparative Examples 1 to 3, i.e., samples in which the average particle size of the NiFe alloy was outside the range, all received an overall evaluation of poor (×). Specifically, for samples in which the average particle size of the NiFe alloy was smaller than the range of this embodiment (Comparative Examples 1 and 2), the initial performance was maintained at good (◯), but the durability was poor (×). This is thought to be because when the average particle size of the NiFe alloy was smaller than the range of this embodiment, the alloying effect was absent (or small). On the other hand, for the sample in which the average particle size of the NiFe alloy was larger than the range of this embodiment (Comparative Example 3), both the initial performance and durability were poor (×). This is thought to be because the effect of Fe as a sintering aid was too high, making the functional layer too dense and making it difficult for gas to pass through. This shows that when the average particle size of the NiFe alloy was in the range of 0.779 to 1.00 μm, the durability was improved while maintaining the initial performance.

[0080] (Relationship between the average particle size of NiFe and that of YSZ particles) As can be seen from a comparison between Examples 1 to 3 and Examples 4 to 6, when the average particle size of the NiFe alloy is 0.779 μm and the pore size ratio is the same, the samples (Examples 1 to 3) in which the size relationship between the average particle size of the NiFe and the average particle size of the YSZ particles satisfies the range of this embodiment show improved durability without a significant decrease in initial performance compared to the samples (Examples 4 to 6) in which this relationship does not satisfy the range. Furthermore, as can be seen from a comparison between Examples 7 to 9 and Examples 10 to 12, when the average particle size of the NiFe alloy is 0.808 μm and the pore size ratio is the same, the samples (Examples 7 to 9) in which the size relationship satisfies the range of this embodiment show slightly improved initial performance and significantly improved durability compared to the samples (Examples 10 to 12) in which this relationship does not satisfy the range. As can be seen from a comparison between Examples 13 to 15 and Examples 16 to 18, when the average particle size of the NiFe alloy is 1.000 μm and the pore size ratio is the same, the samples (Examples 13 to 15) in which the size relationship of the average particle size satisfies the range of this embodiment maintain the initial performance and have significantly improved durability compared to the samples (Examples 16 to 18) that do not satisfy this range. This shows that when the average particle size of the NiFe alloy is within the range of this embodiment and the size relationship between the average particle size of NiFe and the average particle size of YSZ is within the range of this embodiment, durability is improved while maintaining the initial performance.

[0081] (pore diameter ratio) As can be seen from a comparison of Example 2 with Examples 1 and 3, when the average particle size of the FeNi alloy is 0.779 μm and the magnitude relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ is within the range of this embodiment, the sample (Example 2) whose pore size ratio satisfies the range of this embodiment exhibits improved durability while maintaining initial performance compared to the samples (Examples 1 and 3) that do not satisfy this range.A similar tendency is also seen in samples (Examples 7 to 9) where the average particle size of the NiFe alloy is 0.808 μm and the magnitude relationship is within the range of this embodiment, and samples (Examples 13 to 15) where the average particle size of the NiFe alloy is 1.00 μm and the magnitude relationship is within the range of this embodiment.

[0082] Comparing Example 5 with Examples 4 and 6 reveals that when the average particle size of the NiFe alloy is 0.779 μm and the relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ is outside the range of this embodiment, the sample (Example 5) in which the pore size ratio satisfies the range of this embodiment exhibits improved durability while maintaining initial performance compared to the samples (Examples 4 and 6) in which the pore size ratio does not satisfy the range of this embodiment. A similar trend was observed for samples (Examples 10-12) in which the average particle size of the NiFe alloy is 0.808 μm and the relationship is outside the range of this embodiment, and for samples (Examples 16-18) in which the average particle size of the NiFe alloy is 1.00 μm and the relationship is outside the range of this embodiment. This demonstrates that when the pore size ratio satisfies the range of this embodiment, durability is improved while maintaining initial performance.

[0083] As described above, it can be seen that when the average particle size of the NiFe alloy satisfies the range specified in this embodiment, durability can be improved while maintaining initial performance. Furthermore, it can be seen that when the average particle size of the NiFe alloy satisfies the range specified in this embodiment and the relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ particles satisfies the range specified in this embodiment, durability can be further improved. Similarly, it can be seen that when the average particle size of the NiFe alloy satisfies the range specified in this embodiment and the relationship between the average particle size of the YSZ particles and the pore size satisfies the range specified in this embodiment, durability can be further improved. Furthermore, it can be seen that when the particle size of the NiFe alloy satisfies the range specified in this embodiment and the relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ particles and the pore size ratio satisfies the range specified in this embodiment, durability is most improved.

[0084] As can be seen from Comparative Examples 1 to 3, even if the relationship between the average particle size of the NiFe alloy and the average particle size of the YSZ particles or the pore size ratio satisfies the range of this embodiment, durability is low if the average particle size of the NiFe alloy does not satisfy the range of this embodiment.

[0085] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications are possible.

[0086] For example, in the above embodiment, the Ni alloy is an NiFe alloy, but the Ni alloy is not limited to an NiFe alloy.

[0087] The present invention may include the following configurations.

[0088] [1] a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and The fuel electrode is NiFe a functional layer containing an alloy and a conductive solid oxide; The functional layer NiFe The average grain size of the alloy is 0.779 μm or more and 1.00 μm or less, The aforementioned NiFe the average particle size of the alloy is smaller than the average particle size of the conductive solid oxide; Electrochemical cell.

[0090] [2] The aforementioned [1] In the electrochemical cell according to a pore size ratio, which is a ratio of an average particle size of the conductive solid oxide to an average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less; Electrochemical cell.

[0091] [3] a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and The fuel electrode is NiFe a functional layer containing an alloy and a conductive solid oxide; The Ni contained in the functional layer Fe The average grain size of the alloy is 0.779 μm or more and 1.00 μm or less, a pore size ratio, which is a ratio of an average particle size of the conductive solid oxide to an average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less; Electrochemical cell. [4] The aforementioned [3] In the electrochemical cell according to The aforementioned NiFe the average particle size of the alloy is smaller than the average particle size of the conductive solid oxide; Electrochemical cell.

[0092] [5] [1] to [4] The electrochemical cell according to any one of Solid oxide electrolysis cell.

[0093] [6] The aforementioned [5] a plurality of solid oxide electrolysis cells according to the above item 1 are stacked one upon the other; Cell stack.

[0094] [7] The aforementioned [6] a cell stack according to the above; a vaporizer that generates water vapor to be supplied to the cell stack; a heat exchanger that exchanges heat with the gas supplied to the cell stack; a heater for heating the cell stack; a heat insulating material in which the cell stack, the vaporizer, the heat exchanger, and the heater are disposed; Equipped with Hot module.

[0095] [8] The aforementioned [7] The hot module according to claim 1, Gas production equipment. [Industrial Applicability]

[0096] The present invention relates to an electrochemical cell, a solid oxide electrolysis cell, a cell stack, a hot module, and a gas production device.

Claims

1. a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and the anode has a functional layer containing a Ni alloy and a conductive solid oxide; The average particle size of the Ni alloy contained in the functional layer is 0.77 μm or more and 1.00 μm or less, the average particle size of the Ni alloy is smaller than the average particle size of the conductive solid oxide; Electrochemical cell.

2. 10. The electrochemical cell of claim 1, The Ni alloy is a NiFe alloy. Electrochemical cell.

3. 10. The electrochemical cell of claim 1, a pore size ratio, which is a ratio of an average particle size of the conductive solid oxide to an average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less; Electrochemical cell.

4. A solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and the anode has a functional layer containing a Ni alloy and a conductive solid oxide; The average particle size of the Ni alloy contained in the functional layer is 0.77 μm or more and 1.00 μm or less, a pore size ratio, which is a ratio of an average particle size of the conductive solid oxide to an average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less; Electrochemical cell.

5. The electrochemical cell according to claim 4, The Ni alloy is a NiFe alloy. Electrochemical cell.

6. The electrochemical cell according to claim 4, the average particle size of the Ni alloy is smaller than the average particle size of the conductive solid oxide; Electrochemical cell.

7. A solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; and the anode has a functional layer containing a Ni alloy and a conductive solid oxide; The average particle size of the Ni alloy contained in the functional layer is 0.77 μm or more and 1.00 μm or less, The Ni alloy particles are uniformly dispersed in the functional layer. Electrochemical cell.

8. The electrochemical cell of claim 7, The Ni alloy is a NiFe alloy. Electrochemical cell.

9. The electrochemical cell of claim 7, the average particle size of the Ni alloy is smaller than the average particle size of the conductive solid oxide; Electrochemical cell.

10. The electrochemical cell of claim 7, a pore size ratio, which is a ratio of an average particle size of the conductive solid oxide to an average size of the pores contained in the functional layer, is 1.5 or more and 2.6 or less; Electrochemical cell.

11. An electrochemical cell comprising the electrochemical cell according to any one of claims 1 to 10. Solid oxide electrolysis cell.

12. A solid oxide electrolysis cell according to claim 11, wherein a plurality of the solid oxide electrolysis cells are stacked. Cell stack.

13. The cell stack according to claim 12, a vaporizer that generates water vapor to be supplied to the cell stack; a heat exchanger that exchanges heat with the gas supplied to the cell stack; a heater for heating the cell stack; a heat insulating material in which the cell stack, the vaporizer, the heat exchanger, and the heater are disposed; Equipped with Hot module.

14. Equipped with a hot module according to claim 13. Gas production equipment.

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