JP2021155852A - Production method of high temperature steam electrolytic cell, production method of hydrogen electrode layer for high temperature steam electrolytic cell, and production method of solid oxide electrochemical cell - Google Patents

Abstract

To bring a behavior in which a hydrogen electrode layer shrinks closer to a behavior in which an electrolyte layer shrinks as much as possible.SOLUTION: A high temperature steam electrolytic cell of an embodiment of the present invention comprises: a reticulate skeleton; a porous material, which allows a gas to pass through open pores surrounded by the skeleton; and a hydrogen electrode layer that can electrolyze steam, which flows into the open pores, into oxygen ions and hydrogen. The hydrogen electrode layer includes: first particles for forming a skeleton base material; and a composite layer composed with second particles more difficult to be reduced than the first particles, in which the second particles are dispersedly distributed on the surface facing the open pores of the skeleton. A step for forming the composite layer includes: a step in which composite particles, where the second particle adhere to around the first particles, are produced by performing a composite processing to a mixed powder of the first and second particles; and a step in which a precursor of the composite layer is produced by making a paste produced using the composite particles into a sheet.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to solid oxide electrochemical cells, especially high temperature steam electrolysis cells.

Solid oxide electrochemical cells include, for example, a high temperature steam electrolysis cell (SOEC) for producing hydrogen and oxygen by electrolyzing high temperature steam. SOEC is a so-called hydrogen electrode that electrolyzes water vapor to generate hydrogen and oxygen ions, an electrolyte composed of a solid oxide capable of conducting ions at high temperatures, and oxygen ions transmitted from the hydrogen electrode through the electrolyte. It has an oxygen electrode that is released as oxygen. Such a SOEC is capable of producing hydrogen at a low electrolytic voltage due to a high operating temperature. It should be noted that such a solid oxide electrochemical cell can also be operated as a solid oxide fuel cell (SOFC).

In such a solid oxide electrochemical cell, in general, an electrolyte made of a material having high conductivity of oxygen ions and not allowing gas to pass through is applied to an anode and a cathode made of a porous material that allows gas to pass through. It is sandwiched. For example, in the case of SOEC, a porous member through which water vapor can flow is arranged on one outside of the electrolyte in the thickness direction. For example, a hydrogen electrode that electrolyzes water vapor to generate hydrogen and oxygen ions is provided. Be placed.

A composite material of nickel oxide and ceramics is generally used as the porous material constituting such a hydrogen electrode, and for example, sintering of nickel oxide (NiO) and yttria-stabilized zirconia (YSZ). The body is used. In the case of SOEC, unlike SOFC, a relatively high gas pressure, specifically, a partial pressure of water vapor acts inside the porous member forming a hydrogen electrode or the like. For this reason, the porous material constituting the hydrogen electrode for SOCC or the like is a cermet material containing metal and ceramic particles, or a base material having electron / ion mixed conductivity in which metal fine particles functioning as a catalyst are supported. It has been proposed to use.

J. Electrochem.Soc., 154, A619-A626 (2007) J.Electrochem.Soc., 153, A816-A820 (2006)

By the way, electrodes made of the above-mentioned materials have not been demonstrated to have sufficient initial activity and durability for SOCC. In SOEC, a highly humidified reducing gas is introduced into the hydrogen electrode. Therefore, under conditions of low water vapor utilization, metal particles that function as catalysts and electron conduction paths are oxidized, and the catalytic activity in the hydrogen electrode. And leads to a decrease in electron conductivity. Further, oxidation by the introduced gas and reduction by the gas generated by the electrode reaction are repeated on the metal particles, so that the metal particles grow, and the catalytic activity is lowered and the electron conductivity is lowered. It will be remarkable. Therefore, in the hydrogen electrode of SOEC, it is necessary to stably form the skeleton of the network structure (network structure) of the metal particles that serves as a catalytic action and an electron-conducting path.

Such a solid oxide electrochemical cell usually has a layer (hereinafter, referred to as an electrolyte layer) composed of an electrolyte capable of conducting oxygen ions and impermeable to gas. In addition, the solid oxide electrochemical cell is laminated on the outside in the thickness direction of the electrolyte layer, and is composed of a porous material having a skeleton of a network structure and allowing gas to pass through open pores, and hydrogen. It has a layer that functions as a pole (hereinafter referred to as a hydrogen pole layer). When the solid oxide electrochemical cell is SOEC, the hydrogen electrode layer electrolyzes the water vapor flowing into the open pores into oxygen ions and hydrogen.

Such an electrolyte layer and a hydrogen electrode layer have different volume shrinkage rates when sintered. If the difference in volume shrinkage is large and the shrinkage behavior during sintering is different, there is a problem that the electrolyte layer and the hydrogen electrode layer do not adhere well. Therefore, it is required that the behavior of the hydrogen electrode layer contracting be as close as possible to the behavior of the electrolyte layer contracting so that the electrolyte layer and the hydrogen electrode layer are brought into close contact with each other.

An object to be solved by the present invention is to provide a solid oxide electrochemical cell capable of making the behavior of the hydrogen electrode layer contracting as close as possible to the behavior of the electrolyte layer contracting.

The high-temperature steam electrolysis cell according to the embodiment of the present invention has an electrolyte layer composed of an electrolyte capable of conducting oxygen ions and impermeable to gas, and is laminated on the outer side of the electrolyte layer in the thickness direction, and has a network structure. It is composed of a porous material that has a skeleton that forms a gas and allows gas to pass through the open pores, and has a hydrogen electrode layer that can electrolyze the water vapor that has flowed into the open pores into oxygen ions and hydrogen. The hydrogen electrode layer is a layer in which the first particles forming the base material of the skeleton and the second particles that are less likely to be reduced than the first particles are composited, and the open pores of the skeleton are formed. Includes at least one composite layer in which the second particles are dispersed and arranged on a surface facing the surface. In the step of forming the composite layer, the second particles are adhered around the first particles by performing a composite treatment on a powder obtained by mixing the first particles and the second particles. The composite layer includes a composite treatment step of producing composite particles and a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles. The composite layer is formed by sintering the precursor of.

Further, the hydrogen electrode layer for a high-temperature steam electrolysis cell according to the embodiment of the present invention is laminated on the outer side in the thickness direction of an electrolyte layer composed of an electrolyte that can conduct oxygen ions and does not allow gas to pass through, and has a network shape. A hydrogen electrode layer having a structural skeleton and being composed of a porous material that allows gas to pass through open pores, and capable of electrolyzing water vapor flowing into the open pores into oxygen ions and hydrogen. The first particle forming the base material of the above and the second particle which is less likely to be reduced than the first particle are a composite layer, and the second particle on the surface of the skeleton facing the open pores. Contains at least one composite layer in which the particles of the above are dispersedly arranged. In the step of forming the composite layer, the second particles are adhered around the first particles by performing a composite treatment on a powder obtained by mixing the first particles and the second particles. The composite layer includes a composite treatment step of producing composite particles and a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles. The composite layer is formed by sintering the precursor of.

Further, the solid oxide electrochemical cell of the embodiment of the present invention is laminated on the outer side of the electrolyte layer in the thickness direction with an electrolyte layer composed of an electrolyte capable of conducting oxygen ions and impermeable to gas. It has a hydrogen electrode layer made of a porous material having a skeleton forming a network structure and allowing gas to pass through open pores, and the hydrogen electrode layer is a first particle forming a base material of the skeleton. The second particle, which is less likely to be reduced than the first particle, is a composite layer, and the second particle is dispersed and arranged on the surface of the skeleton facing the open pores. Includes at least one composite layer. In the step of forming the composite layer, the second particles are adhered around the first particles by performing a composite treatment on a powder obtained by mixing the first particles and the second particles. The composite layer includes a composite treatment step of producing composite particles and a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles. The composite layer is formed by sintering the precursor of.

According to the embodiment of the present invention, the behavior of the hydrogen electrode layer contracting can be made as close as possible to the behavior of the electrolyte layer contracting so that the electrolyte layer and the hydrogen electrode layer can be brought into good contact with each other, and the hydrogen electrode layer can be reticulated. The skeleton of the structure can be stably formed.

It is sectional drawing which shows the electrolyte of the high temperature steam electrolysis cell of this embodiment, and the structure around it. It is an image which shows the observation result by the scanning electron microscope (SEM) of the hydrogen electrode substrate in the high temperature steam electrolysis cell of this embodiment. It is an image which shows the observation result by the scanning electron microscope (SEM) of the hydrogen electrode substrate in the high temperature steam electrolysis cell of the comparative example. It is a graph which shows the shrinkage behavior of the hydrogen electrode substrate at the time of sintering of the manufacturing example of the high temperature steam electrolysis cell of this embodiment. It is a graph which shows the shrinkage behavior of the hydrogen electrode substrate at the time of sintering of the comparative example of the high temperature steam electrolysis cell of this embodiment. It is a graph which shows the shrinkage behavior at the time of sintering of NiO simple substance. It is a graph which shows the shrinkage behavior at the time of sintering of GDC alone.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below do not limit the present invention, and various modifications can be made without departing from the gist thereof. Further, the schematic diagram referred to in the following description is a diagram showing the positional relationship of each configuration, and the particle size, the ratio of the thickness of each layer, and the like do not always match the actual ones.

The cross-sectional structure of the solid oxide electrochemical cell of the present embodiment around the electrolyte will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the structure of the electrolyte layer and its surroundings in the solid oxide electrochemical cell.

As shown in FIG. 1, the solid oxide electrochemical cell of the present embodiment is a high-temperature steam electrolysis cell (hereinafter referred to as SOEC) 1 that produces hydrogen and oxygen by electrolyzing high-temperature steam. SOEC1 is composed of a layer made of an electrolyte that does not allow gas to pass through (hereinafter referred to as an electrolyte layer) 13 and a porous material that allows gas to pass through, and electrolyzes water vapor that has flowed into open pores into oxygen ions and hydrogen. It has a possible layer (hereinafter referred to as a hydrogen electrode layer) 10. The hydrogen electrode layer 10 is laminated on the outside (one side) of the electrolyte layer 13 in the thickness direction (indicated by the arrow T in FIG. 1).

In the present embodiment, the hydrogen electrode layer 10 is adjacent to the hydrogen electrode active layer 102, which is adjacent to the electrolyte layer 13 and has a film shape, and the hydrogen electrode active layer 102, and is adjacent to the hydrogen electrode active layer 102 in the thickness direction T. It has a hydrogen electrode substrate 101 that is thicker than the hydrogen electrode active layer 102. The hydrogen electrode substrate 101 is made of a material different from the material constituting the hydrogen electrode active layer 102. The hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 are each made of a porous material, and specifically have a network structure skeleton. Further, the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 each have open pores that are at least partially surrounded by a skeleton having a network structure, and the water vapor that has flowed into the open pores can be absorbed. It can be electrolyzed into oxygen ions and hydrogen. The hydrogen electrode substrate 101 faces a water vapor passage (not shown) through which water vapor can flow. The water vapor that has flowed into the open pores in the hydrogen electrode substrate 101 from the water vapor passage further flows into the open pores in the hydrogen electrode active layer 102. The water vapor from the water vapor passage is mainly electrolyzed into oxygen ions and hydrogen in the hydrogen polar active layer 102.

Further, SOEC1 has an oxygen electrode 15 on the opposite side of the hydrogen electrode layer 10 with respect to the electrolyte layer 13 in the thickness direction, which converts oxygen ions from the electrolyte layer 13 into oxygen and releases them into open pores. .. In the present embodiment, a reaction prevention layer 14 for preventing the diffusion and reaction of elements between the oxygen electrode 15 and the electrolyte layer 13 is arranged between the oxygen electrode 15 and the electrolyte layer 13. That is, the SOEC1 of the present embodiment is laminated in the order of the hydrogen electrode substrate 101, the hydrogen electrode active layer 102, the electrolyte layer 13, the reaction prevention layer 14, and the oxygen electrode layer 15 oxygen electrode layer 15. More specifically, a thin film of the hydrogen electrode active layer 102 is formed on the hydrogen electrode substrate 101, and a thin film of the electrolyte layer 13 is further formed on the hydrogen electrode active layer 102. Further, the structure is such that the reaction prevention layer 14 and the oxygen electrode 15 are formed on the electrolyte layer 13.

Next, the materials constituting each layer of SOEC1 of the present embodiment will be described.
The hydrogen electrode layer 10, that is, the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 are produced, for example, by using composite particles in which particles of a plurality of types of metal oxides (first and second particles) are composited. Specifically, in the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102, the first particles forming the base material of the skeleton of the network structure and the second particles that are less likely to be reduced than the first particles are respectively. It is composited by sintering.

As in the production example described later, only the hydrogen electrode substrate 101 may be produced using composite particles, and the hydrogen electrode active layer 102 may be produced using uncomposited particles. In general, since the hydrogen electrode substrate 101 is thicker than the hydrogen electrode active layer 102, the stress reduction described later can be realized even if only the hydrogen electrode substrate 101 is composited.

The first particles forming the base material of the skeleton are at least one oxide selected from the group consisting of Ni (nickel), Co (cobalt), Fe (iron), Cu (copper), and Ru (ruthenium). Yes, including alloys containing these elements.

On the other hand, the second particle is less likely to be reduced than the first particle, and specifically, Ce (cerium), Gd (gadolinium), Sm (samarium), Y (yttrium), Zr (zirconium). ), At least one kind of oxide selected from the group consisting of Sc (scandium), and includes alloys containing these elements. Such second particles include at least one stabilizer selected from the group consisting of _{Y 2} O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , CaO, MgO, CeO _{2, and the like.} Includes stabilized zirconia in which is dissolved. In addition, the second particle contains a dope ceria in _{which CeO 2} is dissolved in one or more oxides selected from the group consisting of _{Sm 2} O ₃ , Gd _{2 O 3, Gd 2} O _3, and Y ₂ O _3.
It is preferable that the particle size of the first particle is 100 nm to 50 μm and the particle size of the second particle is 10 nm to 5 μm.

The material constituting the electrolyte 13 includes at least one stabilizer selected from the group consisting of _{Y 2} O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , CaO, MgO, CeO _{2, and the like.} It is a solid-dissolved stabilized zirconia and a dope ceria in which _{CeO 2} is solid-dissolved with at least one oxide selected from the group consisting of _{Sm 2} O ₃ , Gd ₂ O ₃ and Y ₂ O _3.

The material constituting the reaction prevention layer 14 is a dope ceria in which _{CeO 2} is solid-solved with at least one oxide selected from the group consisting of _{Sm 2} O ₃ , Gd ₂ O ₃ and Y ₂ O _3.

The material constituting the oxygen electrode 15 is a sintered body containing an oxide having a perovskite structure (hereinafter, referred to as perovskite oxide). The perovskite oxide is mainly represented by Ln _1-x A _x B _{1-y Cy} O _3-δ . Examples of Ln include rare earths such as La. Examples of A include Sr, Ca and Ba. Examples of B and C include Cr, Mn, Co, Fe and Ni.
The x, y and δ of the perovskite oxide satisfy the relations of the following formulas (1), (2) and (3).
0 ≦ x ≦ 1 ・ ・ ・ (1)
0 ≦ y ≦ 1 ・ ・ ・ (2)
0 ≦ δ ≦ 1 ・ ・ ・ (3)
In addition to the above-mentioned perovskite oxide, at least one oxide selected from the group consisting of _{Sm 2} O ₃ , Gd ₂ O ₃ , Y ₂ O _3, etc. is used as the material constituting the oxygen electrode 15. It may further contain ceria doped in _{CeO 2.}

(Manufacturing example)
Next, an example of the method for producing SOC1 of the present embodiment will be described.
First, a powder of nickel oxide as first particles (NiO), as a second particles _{(Gd 2 O 3) 0.1 Gd} 2 O 3 so that the composition of _{(CeO 2) 0.9} Dope ceria (GDC) powder is mixed at a weight ratio of 7: 3.

Then, the mixed powder is put into the particle compounding apparatus to perform the compounding process. As the compounding treatment, either a dry type or a wet type may be used. In the dry method, the particles are compounded by applying stress between the particles. In the wet method, water or a polymer solution is sprayed to bond the powders together. By such a compounding treatment, composite particles in which the second particle is adhered around the first particle are produced.
After the compounding treatment, particles (eg, foaming agent) for forming open pores are mixed.

Using the composited NiO / GDC particles, a paste to be a hydrogen electrode substrate 101 is prepared, and the paste is made into a sheet to prepare a precursor of the hydrogen electrode substrate 101, a so-called precursor. The precursor contains a foaming agent to form open pores.

Then, on the precursor of the hydrogen electrode substrate 101, a film of a mixture of NiO and GDC serving as a hydrogen electrode active layer 102, a film of yttria-stabilized zirconia (YSZ) serving as an electrolyte layer 13, and a reaction prevention layer 14 are formed. The GDC film is sequentially formed by the spray coating method. As a result, an unfired laminate in which the precursor of the hydrogen electrode substrate 101, the hydrogen electrode active layer 102, the electrolyte layer 13, and the reaction prevention layer 14 are laminated in this order is formed. Here, the hydrogen polar active layer 102 is prepared by using a mixed powder of uncomposited nickel oxide (NiO) and ceria (GDC).

After that, the laminate is fired (so-called calcining) within the range of 1200 ° C. or higher and 1600 ° C. or lower. The precursor of the hydrogen electrode substrate 101, the hydrogen electrode active layer 102, the electrolyte layer 13, and the reaction prevention layer 14 are each fired until they have a predetermined strength and the layers are in close contact with each other with a predetermined strength.

_{Then, La (Sr) Co (Fe) O 3-δ,} which is the oxygen electrode 15, is formed on the reaction prevention layer 14 of the calcined laminate by a spray coating method. Then, firing (so-called sintering) is performed so that the oxygen electrode 15 is firmly bonded to the reaction prevention layer 14 within the range of 900 ° C. or higher and 1300 ° C. or lower. As a result, SOEC1 as a sintered body in which the hydrogen electrode substrate 101, the hydrogen electrode active layer 102, the electrolyte layer 13, the reaction prevention layer 14 and the oxygen electrode 15 are laminated in this order can be obtained. The composited NiO / GDC particles in the hydrogen electrode substrate 101 thus produced are in a state in which the NiO particles and the GDC particles are more firmly bonded (sintered) by firing.

In the above-mentioned production example, the composition is nickel oxide (NiO) powder as the first particle and (Gd ₂ O ₃ ) _0.1 (CeO ₂ ) _{0.9 as the second particle.} As described above, _{the powder of ceria (GDC) doped with Gd 2} O ₃ was assumed to be mixed at a weight ratio of 7: 3, but the mixing ratio (weight ratio) and the composition of GDC are limited to this. is not it. It is desirable that NiO as the first particle and the powder of GDC as the second particle are mixed at a weight ratio of 5: 5 to 75:25, and the _{amount of (Gd 2} O ₃ ) in the GDC is 0. It is preferably 1 to 0.3.

In the comparative example, a mixed powder obtained by mixing NiO and GDC at a weight ratio of 7: 3 and a solvent were mixed to prepare a paste of the hydrogen electrode substrate 101. That is, the powder is only mixed by a ball mill or the like and is not composited (non-composite powder). The steps other than this were the same as in the examples.

(Observation of structure of hydrogen electrode substrate)
FIG. 2 shows the observation results of the hydrogen electrode substrate 101 of the SOEC1 obtained as described above by a scanning electron microscope (SEM). FIG. 2 is an image showing the observation results of the hydrogen electrode substrate of the high-temperature steam electrolysis cell of the present embodiment by a scanning electron microscope (SEM).

Note that FIG. 3 is an image showing the observation results of the hydrogen electrode substrate of the high-temperature steam electrolysis cell of the comparative example by a scanning electron microscope (SEM). Since the SEM images shown in FIGS. 2 and 3 are reflected electron images, the bright part in the figure corresponds to GDC and the dark part corresponds to NiO.

In the production example of this embodiment, as shown in FIG. 2, it is observed that the sintering of NiO, which is a dark portion, has progressed sufficiently to form a good network structure (network structure). Further, the particles of GDC, which is a bright part, can be uniformly formed on the surface of the skeleton of the network structure of NiO without agglomeration, and it is possible to prevent excessive sintering of NiO that occurs during the operation of SOEC1. It will be possible. The GDC particles (second particles) occupy 10 to 90% of the area of the skeleton of the network structure facing the open pores.

On the other hand, in Comparative Example 1, in Comparative Example 1, although the sintering of NiO in the dark part proceeded sufficiently and a good network structure (network structure) was formed, aggregation of GDC in the bright part was observed. Therefore, it is considered that the sintering of NiO forming the base material of the skeleton having a network structure progresses during the operation, and the function as the hydrogen electrode substrate 101 deteriorates.

(Reduction by operating SOEC)
The hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 of SOEC1 are exposed to a reducing atmosphere in the coexistence of water vapor and hydrogen under high temperature operating conditions of 600 ° C. to 900 ° C. during operation. The hydrogen electrode substrate 101 and the hydrogen electrode active layer 102, which are oxides, are partially reduced under the above-mentioned operating conditions. In the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 of the above-mentioned production example and comparative example, since they are composed of two kinds of particles having different easiness of reduction, that is, the first particle and the second particle, NiO which is easily reduced is produced. It is reduced to Ni with volume shrinkage, and GDC maintains its structure as an oxide.

In the production example, NiO particles (first particles) that are relatively easily reduced form a base material of a skeleton having a uniform network structure, and GDC particles (first particles) that are difficult to be reduced on the surface of the skeleton facing the open pores. 2 particles) are dispersed and arranged. Therefore, the hydrogen electrode base 101 and the hydrogen electrode active layer 102 are uniformly reduced and shrunk under the above-mentioned SOEC operating conditions, and the hydrogen electrode layer 10 including the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 contracts. , The behavior of the electrolyte layer 13 contracting can be as close as possible. Thereby, the stress acting on the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 and the stress acting between the hydrogen electrode active layer 102 and the electrolyte layer 13 can be reduced.

When the GDC is biased as in the comparative example, the reduction shrinkage of the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 is also biased, and the hydrogen electrode substrate 101 and the hydrogen electrode active layer 102 and hydrogen are also biased. Due to the stress generated between the polar active layer 102 and the electrolyte layer 13, microcracks may occur in the hydrogen electrode substrate 101 and the hydrogen polar active layer 102, and the performance of SOC1 may be deteriorated.

(Shrinking behavior during sintering)
The shrinkage behavior of the hydrogen electrode substrate 101 used in the above-mentioned production examples and comparative examples, NiO alone, and GDC alone during sintering was measured. The following shows the shrinkage behavior of the hydrogen electrode substrate during sintering of the production example of the high-temperature steam electrolysis cell of the present embodiment, the shrinkage behavior of the hydrogen electrode substrate during sintering of the comparative example, and the shrinkage behavior of NiO alone during sintering. And, it will be described in comparison with the shrinkage behavior at the time of sintering the GDC alone.

FIG. 4 is a graph showing the shrinkage behavior of the hydrogen electrode substrate at the time of sintering in the production example of the high-temperature steam electrolysis cell of the present embodiment. FIG. 5 is a graph showing the shrinkage behavior of the hydrogen electrode substrate during sintering of the comparative example of the high-temperature steam electrolysis cell of the present embodiment. FIG. 6 is a graph showing the shrinkage behavior of NiO alone during sintering. FIG. 7 is a graph showing the shrinkage behavior of GDC alone during sintering. The calorific value at the time of sintering in the production example shown in FIG. 4 is 807 kJ / mol, and the calorific value at the time of sintering in the comparative example shown in FIG. 5 is 762 kJ / mol. The amount of heat at the time of binding is 372 kJ / mol, and the amount of heat at the time of sintering the GDC alone shown in FIG. 7 is 765 kJ / mol.

The shrinkage behavior of the mixed particles of the NiO particles (first particles) and GDC particles (second particles) shown in FIGS. 4 and 5 at the time of sintering shows that the base material of the skeleton of the network structure is the NiO particles (second particles). Despite the formation of the particles of 1), the shrinkage behavior of NiO alone shown in FIG. 6 during sintering is closer to the shrinkage behavior of GDC alone shown in FIG. 7 during sintering. That is, it is considered that the GDC particles (second particles) dispersed and arranged in the skeleton of the network structure suppress the excessive shrinkage behavior due to the sintering of the NiO particles (first particles). As a result, the behavior of the hydrogen electrode layer 10 contracting can be suppressed, and the behavior of the electrolyte layer 13 contracting can be approached.

Further, by forming a skeleton of a network structure with composite particles in which NiO particles having electron conductivity and GDC particles having ion conductivity are mixed in advance under the operating conditions of SOC1, these particles themselves have good electrons. And can be a conductor of ions, a network structure that conducts electrons and ions can be formed in the hydrogen electrode layer 10, and excessive burning of metal does not occur under the operating conditions of SOEC1. , It becomes possible to maintain high catalytic activity. Further, the particles forming the skeleton of the network structure are composite particles of the first particles forming the base material and the second particles which are less likely to be reduced than the first particles, and the first particles and the second particles are used. It is possible to control the sintering characteristics by adjusting the ratio of the particles to the particles.

[Other Embodiments]
In the above-described embodiment, the hydrogen electrode layer 10 (see FIG. 1) is adjacent to the electrolyte layer 13 and has a film-like hydrogen electrode active layer 102, and is adjacent to the hydrogen electrode active layer 102. The hydrogen electrode active layer 102 is different from the hydrogen electrode active layer 102, and the hydrogen electrode substrate 101 is thicker than the hydrogen electrode active layer 102 in the thickness direction T, and is open in the skeleton of the network structure. The composite layer in which the second particles are dispersed and arranged on the surface facing the pores is assumed to be a hydrogen electrode substrate 101 and a hydrogen electrode active layer 102, but the composite layer according to the present embodiment is in this embodiment. It is not limited. The composite layer according to the present embodiment may be, for example, only the hydrogen electrode substrate 101. By bringing the shrinkage behavior of the hydrogen electrode base 101 and the electrolyte layer 13 during sintering closer to each other, the shrinkage behavior of the thin-film hydrogen pole active layer 102 between them also becomes the hydrogen pole base 101 on both sides in the thickness direction T. And can be brought closer to the electrolyte layer 13.

Further, in the above-described embodiment, the hydrogen electrode layer 10 includes two layers having different materials and thicknesses from the hydrogen electrode active layer 102 and the hydrogen electrode substrate 101, but the hydrogen electrode according to the present embodiment. The layer is not limited to this aspect. The hydrogen electrode layer is a single layer of the same material and the same structure, that is, a single hydrogen electrode (only the hydrogen electrode active layer), and the hydrogen electrode is the second surface of the skeleton of the network structure facing the open pores. It may be a composite layer in which particles are dispersed and arranged.

Further, in the above-described embodiment, the fixed oxide electrochemical cell is a high-temperature steam electrolysis cell (SOEC) 1, but the fixed oxide electrochemical cell according to the present embodiment is limited to this. However, it can also be applied to solid oxide fuel cells (SOFCs).
As described above, according to at least one embodiment, the behavior of the hydrogen electrode layer contracting can be made as close as possible to the behavior of the electrolyte layer contracting.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 High temperature steam electrolysis cell (solid oxide electrochemical cell), 10 hydrogen electrode layer, 101 hydrogen electrode substrate (hydrogen electrode layer, composite layer), 102 hydrogen electrode active layer (hydrogen electrode layer, composite layer), 13 electrolyte layer ( Electrolyte), 14 Anti-reaction layer, 15 Oxygen electrode

Claims (9)

It has an electrolyte layer composed of an electrolyte that can conduct oxygen ions and does not allow gas to pass through, and is laminated on the outside in the thickness direction of the electrolyte layer, has a skeleton of a network structure, and is surrounded by the skeleton. It is made of a porous material that allows gas to pass through the open pores, and has a hydrogen electrode layer that can electrolyze the water vapor that has flowed into the open pores into oxygen ions and hydrogen. The hydrogen electrode layer is the skeleton. The first particle forming the base material of the above and the second particle which is less likely to be reduced than the first particle are a composite layer, and the surface of the skeleton facing the open pores is the first. A method for producing a high-temperature steam electrolysis cell containing at least one composite layer in which two particles are dispersed and arranged.
The step of forming the composite layer is
By performing a compounding treatment on a powder obtained by mixing the first particles and the second particles, composite particles in which the second particles are adhered around the first particles are produced. Processing process and
The composite layer includes a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles, and by sintering the precursor of the composite layer. Is formed,
A method for manufacturing a high-temperature steam electrolysis cell. The precursor of the composite layer contains a foaming agent for forming the open pores.
The method for producing a high-temperature steam electrolysis cell according to claim 1. The first particle is at least one oxide selected from the group consisting of Ni, Co, Fe, Cu, and Ru.
The method for producing a high-temperature steam electrolysis cell according to claim 2, wherein the second particle is at least one oxide selected from the group consisting of Ce, Gd, Sm, Y, Zr, and Sc. The hydrogen electrode layer is
The hydrogen pole active layer adjacent to the electrolyte layer and
A hydrogen electrode substrate that is adjacent to the hydrogen electrode active layer, has a different material from the hydrogen electrode active layer, and has a thicker layer than the hydrogen electrode active layer in the thickness direction.
Including
The method for producing a high-temperature steam electrolysis cell according to any one of claims 1 to 3, wherein the composite layer is at least a hydrogen electrode substrate among the hydrogen electrode substrate and the hydrogen electrode active layer. It is arranged on the opposite side of the hydrogen electrode layer from the electrolyte layer in the thickness direction, and is composed of a porous material that allows gas to pass through. Oxygen ions from the electrolyte layer are converted into oxygen to form open pores. The oxygen electrode to be released and
An anti-reaction layer arranged between the oxygen electrode and the electrolyte layer to prevent the diffusion and reaction of elements between the oxygen electrode and the electrolyte layer,
The method for producing a high-temperature steam electrolysis cell according to any one of claims 1 to 4, further comprising. The particle size of the first particle is 100 nm to 50 μm.
The method for producing a high-temperature steam electrolysis cell according to any one of claims 1 to 5, wherein the particle size of the second particle is 10 nm to 5 μm. The method for producing a high-temperature steam electrolysis cell according to any one of claims 1 to 6, wherein the second particles occupy an area of 10 to 90% on the surface of the skeleton facing the open pores. It is laminated on the outside in the thickness direction of the electrolyte layer composed of an electrolyte that can conduct oxygen ions and does not allow gas to pass through, has a skeleton of a network structure, and gas is supplied to the open pores surrounded by the skeleton. A first particle and a first particle which is a hydrogen electrode layer which is composed of a porous material through which the gas passes and is capable of electrolyzing the water vapor flowing into the open pores into oxygen ions and hydrogen, and which forms the base material of the skeleton. The second particle, which is less likely to be reduced than the particles of, is a composite layer, and at least one composite in which the second particle is dispersed and arranged on the surface of the skeleton facing the open pores. A method for producing a hydrogen electrode layer for a high-temperature steam electrolytic cell including a layer.
The step of forming the composite layer is
By performing a compounding treatment on a powder obtained by mixing the first particles and the second particles, composite particles in which the second particles are adhered around the first particles are produced. Processing process and
The composite layer includes a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles, and by sintering the precursor of the composite layer. Is formed,
A method for manufacturing a hydrogen electrode layer for a high-temperature steam electrolytic cell. An electrolyte layer composed of an electrolyte that can conduct oxygen ions and does not allow gas to pass through.
It has a hydrogen electrode layer that is laminated on the outside in the thickness direction of the electrolyte layer, has a skeleton of a network structure, and is composed of a porous material that allows gas to pass through open pores surrounded by the skeleton. The hydrogen electrode layer is a layer in which the first particles forming the base material of the skeleton and the second particles that are less likely to be reduced than the first particles are composited, and the skeleton is described above. A method for producing a solid oxide electrochemical cell, which comprises at least one composite layer in which second particles are dispersed and arranged on a surface facing open pores.
The step of forming the composite layer is
By performing a compounding treatment on a powder obtained by mixing the first particles and the second particles, composite particles in which the second particles are adhered around the first particles are produced. Processing process and
The composite layer includes a precursor preparation step of preparing a precursor of the composite layer by sheeting a paste prepared by using the composite particles, and by sintering the precursor of the composite layer. Is formed,
A method for producing a solid oxide electrochemical cell.

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