WO2018198352A1

WO2018198352A1 - Solid oxide electrochemical cell and production method therefor

Info

Publication number: WO2018198352A1
Application number: PCT/JP2017/017041
Authority: WO
Inventors: 雅弘浅山; 健太郎松永; 吉野　正人; 隆利浅田; 憲和長田; 理子犬塚; 昌平小林
Original assignee: 株式会社東芝; 東芝エネルギーシステムズ株式会社
Priority date: 2017-04-28
Filing date: 2017-04-28
Publication date: 2018-11-01

Abstract

This solid oxide electrochemical cell (10) has: electrolytes (20) capable of conducting oxygen ions; and a porous member (30) that is laminated on said electrolytes (20). An edge part (33) of the porous member (30) has a lower Young's modulus in the thickness direction than the central part (31) thereof that is situated on the inner side of the edge parts (33).

Description

Solid oxide electrochemical cell and method for producing the same

Embodiments of the present invention relate to a solid oxide electrochemical cell and a method for manufacturing the same.

Solid oxide electrochemical cells include a solid oxide fuel cell (hereinafter referred to as “SOFC”) that generates electricity continuously by an electrochemical reaction by supplying fuel and oxidant from the outside, and high temperature There is a solid oxide electrolysis cell (hereinafter referred to as “SOEC”) that generates hydrogen and oxygen by electrolyzing the water vapor. As a method for producing hydrogen using the SOEC, there is a method of producing hydrogen and oxygen by electrolyzing high-temperature steam, so-called “high-temperature steam electrolysis method”.

Such a solid oxide electrochemical cell is composed of a material having a relatively low toughness such as a solid oxide, that is, a ceramic material or a porous material. For example, SOEC is generally a hydrogen electrode that electrolyzes water vapor to generate hydrogen and oxygen ions, an electrolyte that conducts oxygen ions without passing gas, and an external passage that converts oxygen ions from the electrolyte into oxygen. And an oxygen electrode that flows out into In particular, the hydrogen electrode and the oxygen electrode are composed of porous solid oxides (ceramics) in order to pass water vapor and oxygen, respectively.

JP 2014-041704 A JP 2016-126893 A

In a solid oxide electrochemical cell, a number of single cells composed of a hydrogen electrode, an electrolyte, and an oxygen electrode are stacked in the thickness direction to form a cell stack. A separator is disposed between adjacent single cells in the thickness direction. In such a cell stack, when a plurality of single cells and separators are assembled, damage such as cracks may occur in a member made of a porous material. It is difficult to detect breakage such as a crack generated in the cell stack. Therefore, there is a demand for a solid oxide electrochemical cell having a structure or material that is unlikely to break even when a relatively large stress is applied to a single cell when a cell stack is formed.

The problem to be solved by the present invention is to provide a solid oxide electrochemical cell that is not easily damaged even when a relatively large stress is applied to members constituting the single cell.

A solid oxide electrochemical cell according to an embodiment of the present invention includes an electrolyte capable of conducting oxygen ions, and a porous member laminated on the electrolyte, and an edge of the porous member is the edge. The Young's modulus in the thickness direction is lower than that of the central portion on the inside of the plate.

It is sectional drawing of the solid oxide electrochemical cell of this embodiment. It is sectional drawing which decomposed | disassembled the solid oxide electrochemical cell of this embodiment. It is a flowchart explaining a manufacturing process until the sintered compact of a porous member is obtained from mixed powder among the manufacturing methods of the solid oxide electrochemical cell of this embodiment. It is a figure which shows the arrangement | positioning relationship of the 1st laminated body which forms the porous member of the solid oxide electrochemical cell of this embodiment, and a 2nd laminated body.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the scope of the invention.

[Configuration example of solid oxide electrochemical cell]
First, a schematic configuration of the solid oxide electrochemical cell of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of the solid oxide electrochemical cell of this embodiment. FIG. 2 is an exploded cross-sectional view of the solid oxide electrochemical cell of this embodiment. In each figure, the thickness direction of the electrolyte layer of the solid oxide electrochemical cell is indicated by an arrow T.

As shown in FIGS. 1 and 2, the solid oxide electrochemical cell 10 of this embodiment is a so-called solid oxide electrolysis cell (SOEC) that generates hydrogen and oxygen by electrolyzing high-temperature water vapor. In the following description, it will be referred to as a single cell 10. The single cell 10 has a dense electrolyte 20 that does not allow gas to pass through, and a hydrogen electrode 30 and an oxygen electrode 50 that are porous materials through which gas passes. The hydrogen electrode 30 and the oxygen electrode 50 are disposed outside the electrolyte 20 in the thickness direction T, respectively. The electrolyte 20 is sandwiched between the hydrogen electrode 30 and the oxygen electrode 50.

The electrolyte 20 is made of a material that can conduct oxygen ions and does not pass gas. The electrolyte has a plate shape extending in a direction perpendicular to the thickness direction T thereof. In the case of SOEC, the electrolyte 20 conducts oxygen ions from the hydrogen electrode 30 to the oxygen electrode 50.

As a material constituting the electrolyte 20, for example, stabilized zirconia (for example, yttria stabilized zirconia (YSZ)), perovskite oxide, or ceria (CeO ₂ ) based electrolyte solid solution yttria stabilized zirconia (YSZ) is used. It is done.
Stabilized zirconia is zirconia in which a stabilizer is dissolved in zirconia. Examples of the stabilizer include Y ₂ O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , Nd ₂ O ₃ , CaO, and MgO. Examples of the perovskite oxide include LaSrGaMg oxide, LaSrGaMgCo oxide, and LaSrGaMgCoFe oxide. As the ceria-based electrolyte solid solution, a solid solution in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , or the like is dissolved in a material containing CeO ₂ can be given.

The hydrogen electrode 30 is disposed outside the electrolyte 20 in the thickness direction, and is stacked adjacent to the electrolyte 20. The hydrogen electrode 30 is made of a porous material that allows gas to pass through open pores. In the case of SOEC, the hydrogen electrode 30 receives supply of water vapor from a water vapor passage and electrolyzes the water vapor to generate hydrogen and oxygen ions.

The hydrogen electrode 30 includes catalyst particles and oxygen ion conductive oxide particles. Examples of the catalyst include metals such as nickel, silver, and platinum, and metal oxides such as nickel oxide and cobalt oxide. Examples of the oxygen ion conductive oxide include ceria-based oxides such as samaria-stabilized ceria (SDC) or gadolinia-stabilized ceria (GDC), or zirconia-based oxides such as yttria-stabilized zirconia (YSZ). Can be mentioned.
As an example, a sintered body of nickel oxide (NiO) and yttria stabilized zirconia (YSZ) is used as a material constituting the hydrogen electrode 30.

The oxygen electrode 50 is disposed on the opposite side of the hydrogen electrode 30 and the thickness direction T with respect to the electrolyte 20. The oxygen electrode 50 is made of a porous material that allows gas to pass through. The oxygen electrode 50 releases oxygen ions from the oxygen electrode 24 into the air passage as oxygen.

Examples of the material constituting the oxygen electrode 50 include lanthanum, strontium, manganese (LaSrMn) -based perovskite oxide (LSM), LaSrCo oxide (LSC), LaSrCoFe oxide (LSCF), LaSrFe oxide (LSF), LaSrMnCo oxide (LSMC), LaSrMnCr oxide (LSMC), LaCoMn oxide (LCM), LaSrCu oxide (LSCu), LaSrFeNi oxide (LSFN), LaNiFe oxide (LNF), LaBaCo oxide (LBC), LaNiCo Oxide (LNC), LaSrAlFe oxide (LSAF), LaSrCoNiCu oxide (LSCNC), LaSrFeNiCu oxide (LSFNC), LaNi oxide (LN), GdSrCo oxide (GSC), GdSrM Oxide (GSM), PrCaMn oxide (PCaM), PrSrMn oxide (PSM), PrBaCo oxide (PBC), SmSrCo oxide (SSC), NdSmCo oxide (NSC), BiSrCaCu oxide (BSCC), BaLaFeCo oxidation (BLFC), BaSrFeCo oxide (BSFC), YSrFeCo oxide (YLFC), YCuCoFe oxide (YCCF), or YBaCu oxide (YBC).

The single cell 10 has a reaction suppression layer 40 that suppresses element diffusion and reaction between the oxygen electrode 50 and the electrolyte 20 during sintering (when the single cell 10 is manufactured). The reaction suppression layer 40 is made of a dense material that does not allow gas to pass through, and can conduct oxygen ions. That is, the single cell 10 is laminated in the order of the hydrogen electrode 30, the electrolyte 20, the reaction suppression layer 40, and the oxygen electrode 50.

In this embodiment, the hydrogen electrode 30, the electrolyte 20, the reaction suppression layer 40, and the oxygen electrode 50 are each rectangular (for example, approximately square) when viewed from the thickness direction T. The hydrogen electrode 30, the electrolyte 20, and the reaction suppression layer 40 have a substantially rectangular shape, and the oxygen electrode 50 has a smaller rectangle (for example, a substantially square shape) such as the hydrogen electrode 30.

That is, the single cell 10 of this embodiment is a hydrogen electrode support type in which the hydrogen electrode 30 side is a support. In this case, the entire hydrogen electrode 30 does not need to function as an original hydrogen electrode. The hydrogen electrode 30 may have a two-layer structure of a lower base layer and an upper hydrogen electrode active layer in the figure, and only the hydrogen electrode active layer may have the original function of the hydrogen electrode. However, the constituent materials of the base layer and the hydrogen electrode active layer can be made substantially the same. In this case, there is no substantial difference between the base material layer and the hydrogen electrode active layer, and the entire hydrogen electrode 30 can serve as both the base material layer and the hydrogen electrode active layer.

In addition, it can also be set as the oxygen electrode support type single cell which uses an oxygen electrode side as a support body. In this case, the electrolyte 20, the reaction suppression layer 40, and the oxygen electrode 50 have a substantially rectangular shape, and the hydrogen electrode 30 has a smaller rectangle (for example, a substantially square shape) such as the oxygen electrode 50.

The single cell 10 configured as described above is disposed between the two

separators

80 and 90. In the thickness direction T, a plate-like conductor (hereinafter referred to as a conductor plate) 60 for passing a current through the single cell is sandwiched between the separator 80 and the hydrogen electrode 30. Similarly, a conductor plate 65 is sandwiched between the separator 90 and the oxygen electrode 50.

Further, a clamping plate 70 is disposed between the separator 80 and the separator 90. In the direction perpendicular to the thickness direction T, the inner edge 72 of the fastening plate 70 is in contact with the edge 44 of the reaction suppression layer 40. The clamping plate 70 applies a clamping force (indicated by an arrow F in FIG. 1) to the single cell 10 through the edge portion 44. Between the reaction suppression layer 40 including the outer edge portion 44 and the separator 80, there are the conductor plate 60, the hydrogen electrode 30, and the electrolyte 20, and among these members, the edge portion 33 particularly has stress caused by the fastening force F. Is working. If the stress is large, damage such as cracks may occur in the porous member of the single cell 10 made of a porous material, for example, the hydrogen electrode 30.

Therefore, in the single cell 10 according to the present embodiment, the hydrogen electrode 30 that is a porous member has a Young's modulus in the thickness direction T at the edge 33 compared to the central portion 31 inside the edge 33. Is configured to be low. The Young's modulus of the edge portion 33 can be set to, for example, 130 GPa or less near room temperature.
As a result, the bending strength and compressive strength of the edge portion 33 are greater than those of the central portion 31. For example, the bending strength of the edge 33 near room temperature can be 50 MPa or more, and the compressive strength can be 150 MPa or more.
Here, it is preferable that the variation in Young's modulus near the room temperature at the edge 33 is small, for example, 10 GPa or less.

In FIG. 1, the boundary between the central portion 31 and the edge portion 33 of the hydrogen electrode 30 (the outer periphery of the central portion 31) coincides with the outer periphery of the oxygen electrode 50. By making the central portion 31 of the hydrogen electrode 30 and the oxygen electrode 50 correspond to each other, it is easy to achieve both reduction of Young's modulus (improvement of strength) of the edge portion 33 and securing of the performance of the single cell 10.

Here, the outer periphery of the central portion 31 and the oxygen electrode 50 may not coincide. For example, the outer periphery of the central part 31 may surround the outer periphery of the oxygen electrode (larger than the outer periphery of the oxygen electrode). Conversely, the outer periphery of the central portion 31 may be surrounded by the outer periphery of the oxygen electrode (smaller than the outer periphery of the oxygen electrode). In short, it is only necessary that the central portion 31 and the oxygen electrode 50 are arranged in correspondence.
In addition, the boundary between the central portion 31 and the edge portion 33 of the hydrogen electrode 30 is preferably located on the outer peripheral side from the equidistant point (1/2 point) between the center and the outer periphery of the hydrogen electrode 30, and moreover, one half. It is preferable that the point is closer to the center than the equidistant point (three quarters) on the outer periphery.

According to the unit cell 10 of the present embodiment, when the stress due to the fastening force F described above is applied to the hydrogen electrode 30, the edge 33 is distorted according to the stress, and the stress acting on the edge 33. To ease. As a result, even if a relatively large stress is applied to the edge 33, the hydrogen electrode 33, which is a porous member, is less likely to be damaged, such as a crack.

Here, when the hydrogen electrode 30 has a two-layer structure of a base material layer and a hydrogen electrode active layer, the Young's modulus of the central portion 31 and the edge portion 33 may be different only in the base material layer. This is because, in general, the base material layer is thicker than the hydrogen electrode active layer, and therefore when the stress is applied, the base material layer is more easily broken.

Thus, the Young's modulus of the edge portion 33 and the central portion 31 can be made different by making the porosity (ratio occupied by open pores per unit volume) different. Specifically, the edge 33 of the hydrogen electrode 30 is configured to have a higher porosity than the center 31.

At this time, the porosity of the edge portion 33 and the central portion 31 is 33% or more, 75% or less, 25% or more, and 65% or less (more preferably 60% or more, 72% or less, 50% or more, 60% or less), respectively. (However, the porosity of the edge portion 33 is higher than that of the central portion 31). By appropriately varying the porosity of the edge portion 33 and the central portion 31, the function as the hydrogen electrode 30 can be secured in the central portion 31 while lowering the Young's modulus of the edge portion 33.
In the examples described later, the porosity of the edge portion 33 is set to 30 to 50%, but the Young's modulus can be further reduced (strength improvement) by making the porosity higher than this range.

Instead of making the porosity different between the central portion 31 and the edge portion 33, or while making the porosity different, the metal content of the central portion 31 and the edge portion 33 may be made different. By making the metal content of the edge portion 33 larger than that of the central portion 31, the Young's modulus of the edge portion 33 can be made lower than that of the central portion 31. For example, metal is not added to the central portion 31 but metal is added to the edge portion 33. By interposing the metal material between the oxide particles constituting the hydrogen electrode 30, the Young's modulus of the edge portion 33 is lowered according to the amount of the metal material added.
As this metal, for example, a metal which is not easily oxidized such as Pt (platinum), Au (gold), Ag (silver) can be used.

When no metal is added to the central portion 31, the amount of metal added to the edge portion 33 is preferably 1% or more and 15% or less (more preferably 2% or more and 10% or less). By adding an appropriate amount to the edge 33 without substantially adding metal to the center 31, the function as the hydrogen electrode 30 can be secured at the center 31 while lowering the Young's modulus of the edge 33.

Here, the addition amount (for example, 1%) is the ratio of the weight W of the additive (here, metal) to the weight W0 of the ceramic components (catalyst and oxide) of the hydrogen electrode 30 (ceramic weight% = (W / W0) * 100). Hereinafter, similarly, the addition amount is expressed by ceramic weight%.
In addition, the additive amount (ceramic weight%) of the additive (for example, metal) that does not vaporize in the subsequent firing becomes substantially constant before and after firing.

When the porosity is different between the central portion 31 and the edge portion 33 and a metal is added to the edge portion 33, the porosity of the edge portion 33 and the central portion 31 is 30% or more, 70% or less, and 25% or more, respectively. 60% or less, and the addition amount of metal is 3% or more and 8% or less (more preferably, the porosity is 55% or more, 65% or less and 50% or more and 60% or less, and the addition amount of metal is 4% or more and 6% or less) (however, the porosity of the edge portion 33 is larger than that of the central portion 31).

The above description is based on the assumption that the unit cell 10 is of the hydrogen electrode support type. In the case of an oxygen electrode-supported single cell, the edge of the oxygen electrode (support layer) may be configured such that the Young's modulus in the thickness direction T is lower than the central part inside the edge.

A method of manufacturing a single cell including the porous member described above (in this embodiment, the hydrogen electrode 30) will be described below.

[Method for producing solid oxide electrochemical cell]
An example of the manufacturing method of the solid oxide electrochemical cell of this embodiment is demonstrated with reference to FIG.3 and FIG.4. FIG. 3 is a flowchart for explaining the manufacturing process until the sintered body of the porous member is obtained from the mixed powder in the manufacturing method of the solid oxide electrochemical cell of the present embodiment. FIG. 4 is a diagram showing an arrangement relationship between the first stacked body and the second stacked body that form the porous member of the solid oxide electrochemical cell of the present embodiment.

First, a method for manufacturing an unfired porous member for forming a solid oxide electrochemical cell will be described. In this production example, the unfired porous member is, for example, the hydrogen electrode 30 (base material layer). The hydrogen electrode 30 includes an edge portion 33 and a central portion 31 having different Young's moduli. The edge portion 33 has a higher porosity, which is a ratio occupied by open pores per unit volume, compared to the central portion 31.

First, in step S02, a mixed powder to be a base material layer (hydrogen electrode 30) including the edge portion 33 and the central portion 31 is created. Specifically, NiO (nickel oxide) powder and YSZ (yttria stabilized zirconia) powder are mixed using methyl ethyl ketone, which is an organic solvent. In this production example, NiO is 40 g, YSZ is 60 g, and methyl ethyl ketone is 100 g. Thereby, a NiO-YSZ mixed powder is prepared.

In order to manufacture the central portion 31 of the porous member, first, in step S10, a slurry to which spacers (for example, resin particles) capable of forming open pores of the central portion 31 are added at a predetermined ratio is prepared. create. The slurry is a mixture of NiO-YSZ mixed powder dispersed in a liquid. Specifically, the NiO—YSZ mixed powder prepared in step S01 is charged into a liquid, and the mixed powder is dispersed in the liquid to prepare a slurry. 1% of tridecyl ether acetic acid (formal name: sodium polyoxyethylene tridecyl ether acetate) was added to the slurry as a dispersion (dispersing agent) for dispersing the mixed powder. As described above, the addition amount 1% is expressed by the ratio (ceramic weight%) of the weight W of the additive (here, the dispersant) to the weight W0 of the ceramic component (here, NiO—YSZ mixed powder). Is done.
Moreover, PVB (polyvinyl butyral) was added as a binder. The amount of the binder (PVB) added is 4% (ceramic weight%).

In addition, acrylic resin particles having a particle diameter of about 1 μm were added to the above-mentioned slurry as spacers for forming pores, so-called pore forming agents. The added amount of the spacer is 5% (ceramic weight%). This ratio is referred to as “first ratio” below. That is, in the step S10, a slurry (hereinafter referred to as a first slurry) in which spacers were added at a first ratio (5%) was created.

The spacer is removed in a later step (sintering step) to create a void in the sintered body. Specifically, the spacer communicates with the outer surface of the sintered body, so-called open pore (open pore). ).

Then, in step S12, an unfired body of porous material (hereinafter referred to as a first sheet) in which the first slurry is formed into a sheet shape is created. Specifically, the first slurry (spacer addition amount 5%) prepared in step S10 is passed through a slit having a gap width of 500 μm to form a sheet and dried. A doctor blade method may be used. In this production example, the first sheet has a thickness of 150 μm. The first sheet is formed into a square shape having a side of 130 mm (see FIG. 4).

And in step S14, as shown with the broken line in FIG. 4, the unbaking body (henceforth a 1st laminated body) 31B which laminates | stacks a some 1st sheet | seat and forms the center part 31 of a porous member. create. In this production example, a plurality of first sheets having the same shape and the same dimensions described above are stacked to create a first stacked body 31B having a predetermined thickness.

On the other hand, in order to manufacture the edge portion 33 of the porous member, first, in step S20, the spacer capable of forming the open pores of the edge portion 33 has a higher ratio than the above-described first ratio (5%) ( Hereinafter, a slurry (hereinafter simply referred to as “second slurry”) that is added simply by “second ratio”) is prepared. In this production example, the same spacer as the first slurry is used as the spacer added to the second slurry. The added amount of the spacer is 20% (ceramic weight%). That is, in the step S20, a second slurry was prepared in which spacers were added at the second ratio (20%).

Then, in step S22, an unfired body (hereinafter referred to as a second sheet) of a porous material in which the second slurry is formed into a sheet shape is created. Specifically, the second slurry (spacer addition amount 20%) created in step S20 is passed through the slits described above to form a sheet and dried. In this production example, the second sheet is formed in the same square shape as the first sheet, but the length of one side thereof is larger than that of the first sheet and is 150 mm. The thickness of the second sheet is the same as that of the first sheet.

In step S24, a plurality of second sheets are laminated to form an unfired body (hereinafter referred to as a second laminated body) 33B that forms the edge 33 of the porous member. In the present manufacturing example, a plurality of second sheets having the same shape and the same dimensions as described above are stacked to create a second stacked body 33B having substantially the same thickness as the first stacked body 31B.

Then, in step S26, a through hole having a size and shape corresponding to the first stacked body 31B is formed in the second stacked body 33B. As shown in FIG. 4, in the present manufacturing example, a square through hole 35 having a side of 130 mm corresponding to the first stack 31B is formed in the center of the second stacked body 33B having a side of 130 mm. To do. The through hole 35 may be slightly larger than the dimension of the first stacked body 31B.

And in step S30, the 1st laminated body 31B is arrange | positioned inside the 2nd laminated body 33B, and an unbaking porous member is created. Specifically, in step S26, the first stacked body 31B having a shape corresponding to the through hole 35 is inserted into the through hole 35 formed in the center of the second stacked body 33B. That is, the first stacked body 31B is fitted inside the second stacked body 33B on the same plane.

In this production example, the first laminate 31B and the second laminate 33B are integrated by thermocompression bonding at a predetermined temperature (for example, 60 ° C.) and a predetermined pressure (10 MPa). Thus, an unfired porous member having a central portion 31 in which the added amount of spacer is 5% and an edge portion 33 surrounding the central portion 31 and having an added amount of spacer of 20% is created.

In this production example, the unfired porous member is an unfired body of a hydrogen electrode that forms a solid oxide electrochemical cell. Therefore, on the porous member (hydrogen electrode 30), the layer of the electrolyte 20, the electrolyte, and the reaction suppression layer are laminated in the thickness direction and calcined.

First, a slurry for producing the electrolyte 20 is prepared. Specifically, an electrolyte slurry is prepared using YSZ (yttria stabilized zirconia) powder. Unlike the porous member described above, the electrolyte layer is a dense layer that does not pass gas. For this reason, it is not necessary to add a spacer as described above to the slurry for electrolyte.

The reaction suppression layer 40 uses a powder of ceria (hereinafter referred to as GDC) doped with Gd ₂ O ₃ to have a composition of (Gd ₂ O ₃ ) _0.1 (CeO ₂ ) _0.9. Create a slurry for the layer. Similar to the electrolyte 20 layer, the reaction suppression layer 40 is a dense layer that does not allow gas to pass through, and the addition of a spacer is not necessary.

The screen of the slurry for electrolyte is screen-printed on the surface of the above-mentioned unfired porous member to form an unfired electrolyte layer. Further, a slurry for reaction suppression layer is screen-printed on the surface of the electrolyte layer to form an unfired reaction suppression layer. In the present production example, the electrolyte layer and the reaction suppression layer have a square shape with a side of 150 mm, as in the porous member described above. In this way, an unfired molded body is produced in which the porous member (hydrogen electrode), the electrolyte, and the reaction suppression layer are laminated in this order.

The unfired molded body is degreased by heating in the atmosphere at a temperature of 600 ° C. for 2 hours. The degreased molded body is further heated (calcined) at a temperature of 1500 ° C. for 2 hours to obtain a fired body in which the hydrogen electrode 30, the electrolyte 20, and the reaction suppression layer 40 are laminated in this order.

Then, an oxygen electrode 50 is further formed on the surface of the reaction suppression layer 40 in the obtained fired body. First, a slurry for producing the oxygen electrode 50 is prepared. Specifically, a slurry for an oxygen electrode is prepared using LSCF (LaSrCoFe oxide) powder. Since the oxygen electrode 50 is a porous member through which gas passes, a spacer for forming open pores is added to the slurry. A slurry for the oxygen electrode is screen-printed on the surface of the reaction suppressing layer 40 in the fired body to form an unfired oxygen electrode layer. By heating this at a temperature of 1000 ° C. in the atmosphere, a sintered body of the solid oxide electrochemical cell 10 in which the hydrogen electrode 30, the electrolyte 20, the reaction suppression layer 40, and the oxygen electrode 50 are laminated in this order is obtained. As a result of this sintering, in the hydrogen electrode 30, the first laminated body 31B and the second laminated body 33B shown in FIG. 4 are completely bonded together to form a porous member sintered body (step S40).

At this time, the oxygen electrode 50 (slurry for the oxygen electrode) is printed and fired so as to form a square shape with a side of 100 mm. That is, the oxygen electrode 50 is disposed in the region of the central part 31 of the hydrogen electrode 30 (the area is smaller than that of the central part 31).

In the porous member 30 (sintered body) manufactured as described above, the edge portion 33 has a higher porosity, which is the ratio of open pores per unit volume, than the central portion 31. The edge portion 33 having a high porosity has a lower Young's modulus E in the thickness direction T than the center portion 31.

For example, when the added amount of the spacer (ceramic weight%) in the second slurry (see Step S20) for forming the edge 33 of the porous member, that is, the second ratio is 20%, the porosity is 40%. Yes, Young's modulus is 110 GPa. Further, when the second ratio is 25%, the porosity is 50%. When the second ratio is 15%, the porosity is 35% and the Young's modulus is 119 GPa. When the second ratio is 5%, the porosity is 30% and the Young's modulus is 145 GPa. In this way, the Young's modulus of the edge 33 can be controlled by adjusting the amount of spacer added, that is, the porosity.

In the above-described embodiment, the edge 33 of the porous member has a lower Young's modulus in the thickness direction T than that of the central portion 31 by increasing the amount of spacer added compared to the central portion 31. However, the method of reducing the Young's modulus as compared with the central portion 31 is not limited to this.

For example, it is also preferable to add a metal that is not added to the material constituting the central portion 31, that is, the first slurry, to the material constituting the edge portion 33, that is, the second slurry (increase the addition amount).

For example, in step S20, 10% by weight of acrylic resin particles as a spacer is added to the second slurry as ceramic weight%, and Ag (silver) not included in the first slurry (step S10) is added to the ceramic. It is also preferable to add 5% by weight. In this case, although the porosity was 33%, the Young's modulus was 120 GPa, and substantially the same Young's modulus as when the porosity was 35% (Young's modulus was 119 GPa) could be realized.

In the embodiment described above, the porous member that has different Young's modulus and porosity at the edge and the center is the hydrogen electrode 30, but the porous member according to the present invention is not limited to this. It is not something. The present invention can be applied to any porous member that forms part of a solid oxide electrochemical cell such as an oxygen electrode.

According to at least one embodiment described above, even if a relatively large stress acts on the members constituting the single cell, it is possible to make it difficult to cause breakage.

Although several 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 forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims

An electrolyte capable of conducting oxygen ions;
A porous member laminated on the electrolyte;
With
The edge part among the said porous member has a lower Young's modulus of the said thickness direction compared with the center part inside the said edge part. Solid oxide electrochemical cell.
The solid oxide electrochemical cell according to claim 1, wherein the edge portion has a higher porosity than the central portion.
The solid oxide electrochemical cell according to claim 1 or 2, wherein the material constituting the edge portion has a larger amount of metal material added than the material constituting the central portion.
The porous member is a hydrogen electrode capable of electrolyzing water vapor into oxygen ions and hydrogen,
An oxygen electrode that is disposed on the opposite side of the hydrogen electrode with respect to the electrolyte so as to correspond to the central portion, is made of a porous material that allows gas to pass through, and further discharges oxygen ions from the electrolyte as oxygen. A solid oxide electrochemical cell according to any one of claims 1 to 3.
Creating a first slurry with spacers added in a first ratio;
Creating a first sheet from the first slurry;
Creating a second slurry in which spacers are added at a second ratio that is higher than the first ratio;
Creating a second sheet from the second slurry;
Combining the second sheet and the first sheet to create an unfired porous member;
Sintering the green porous member to create a sintered body of the porous member;
A method for producing a solid oxide electrochemical cell comprising:
The step of creating the second sheet has a step of forming a through hole having a size and shape corresponding to the first sheet in the second sheet,
The step of creating the unfired porous member has a step of inserting the first sheet into the through hole.
The manufacturing method of the solid oxide electrochemical cell of Claim 5.
The first sheet is a laminate in which a plurality of sheets composed of the first slurry are laminated,
The second sheet is a laminate obtained by laminating a plurality of sheets composed of the second slurry.
The manufacturing method of the solid oxide electrochemical cell of Claim 6.
8. The solid according to claim 5, wherein in the step of creating the unfired porous member, the first sheet and the second sheet are integrated by pressure bonding at a predetermined temperature and a predetermined pressure. A method for producing an oxide electrochemical cell.