Fuel electrode for solid oxide electrochemical cell, electrochemical cell, cell with separator, electrochemical stack, hot module, hydrogen producing apparatus, and method for manufacturing fuel electrode

Abstract

To provide a fuel electrode for a solid oxide electrochemical cell which can easily reduce warpage thereof, an electrochemical cell, a cell with a separator, an electrochemical stack, a hot module, a hydrogen producing apparatus, and a method for manufacturing a fuel electrode.SOLUTION: A fuel electrode for a solid oxide electrochemical cell includes a sintered body including a supporter and a functional layer that is disposed on the surface of the supporter and has a lower porosity than the supporter. A constraining layer is disposed on the back surface of the supporter along the inner periphery of a portion where the functional layer and the supporter overlap each other in a thickness direction, and the contraction rate of the constraining layer during firing is smaller than the contraction rate of the supporter during firing.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an anode for a solid oxide electrochemical cell, an electrochemical cell, a cell with a separator, an electrochemical stack, a hot module, a hydrogen production device, and a method for producing an anode. [Background technology]

[0002] Patent Document 1 discloses a prior art technique in which a green body is sintered under pressure in order to reduce warping of an anode for a solid oxide electrochemical cell produced by sintering the green body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-282817 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, the operation of applying pressure to the molded body to reduce warpage is cumbersome.

[0005] The present invention has been made to solve this problem, and aims to provide a fuel electrode for a solid oxide electrochemical cell, an electrochemical cell, a cell with a separator, an electrochemical stack, a hot module, and a hydrogen production device, as well as a method for producing a fuel electrode, which can easily reduce warping. [Means for solving the problem]

[0006] A first aspect for achieving this objective is a fuel electrode for a solid oxide electrochemical cell comprising a sintered body including a support and a functional layer disposed on the surface of the support and having a lower porosity than the porosity of the support, wherein the fuel electrode comprises a constraining layer disposed on the back surface of the support along the inner periphery of the portion where the functional layer and the support overlap in the thickness direction, and the shrinkage rate of the constraining layer during sintering is smaller than the shrinkage rate of the support during sintering.

[0007] In the second embodiment, in the first embodiment, the inner periphery of the constraining layer has a diameter that decreases toward the rear surface of the support in the thickness direction of the constraining layer.

[0008] A third aspect is a solid oxide electrochemical cell comprising a solid electrolyte and an anode arranged on a back surface of the solid electrolyte, the cell including the anode of the first or second aspect, and the sintered body including, in order from the front surface to the back surface, a solid electrolyte, a functional layer, a support, and a constraint layer.

[0009] A fourth aspect is the third aspect, further comprising an air electrode disposed on a surface of the solid electrolyte, and the constraining layer includes an overlapping portion where the air electrode overlaps in the thickness direction.

[0010] In a fifth aspect, in the fourth aspect, the length of the overlapping portion in a planar direction perpendicular to the thickness direction is 24% or less of the length of the air electrode in the planar direction.

[0011] In a sixth aspect, the battery of the third aspect further includes an air electrode disposed on a surface of the solid electrolyte, and the constraining layer is positioned outside the portion where the air electrode overlaps in the thickness direction.

[0012] A seventh aspect is a separator-equipped cell comprising an electrochemical cell according to any one of the third to sixth aspects and a separator with a central opening disposed on a solid electrolyte, wherein the diameter of the separator opening is greater than the diameter of the inner circumference of the constraining layer.

[0013] An eighth embodiment is an electrochemical stack comprising a plurality of electrochemical cells according to any one of the third to sixth embodiments stacked together.

[0014] A ninth aspect is a hot module comprising an electrochemical stack in the eighth aspect, a vaporizer that generates water vapor supplied to the electrochemical stack, a heat exchanger that exchanges heat with gas supplied to the electrochemical stack, a heater for heating the electrochemical stack, and insulation in which the electrochemical stack, vaporizer, heat exchanger and heater are disposed.

[0015] A tenth aspect is a hydrogen production device including the hot module according to the ninth aspect.

[0016] An eleventh aspect is a method for manufacturing a fuel electrode for a solid oxide electrochemical cell comprising a sintered body including a support and a functional layer disposed on the surface of the support and having a porosity lower than that of the support, the method comprising: a first molding step of laminating a molded body of the functional layer on the surface of the molded body of the support; a second molding step of obtaining a laminate in which a molded body of the constraining layer is disposed on the back surface of the molded body of the support along the inner periphery of the portion where the molded bodies of the functional layer overlap in the thickness direction; and a sintering step of sintering the laminate, wherein the shrinkage rate of the constraining layer during sintering is smaller than the shrinkage rate of the support during sintering. Effect of the Invention

[0017] According to the present invention, a constraining layer is disposed along the periphery of the back surface of the support inside the periphery of the portion where the functional layer and the support overlap in the thickness direction of the solid oxide electrochemical cell fuel electrode. Since the porosity of the functional layer is lower than that of the support and the shrinkage rate of the constraining layer during firing is smaller than that of the support, the warping of the fuel electrode can be easily reduced by the constraining layer. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of an electrochemical stack in one embodiment. [Diagram 2] FIG. 2 is an exploded view of the electrochemical stack. [Diagram 3] FIG. 3A is a cross-sectional view of a cell with a separator, and FIG. 3B is a bottom view of the cell with a separator as viewed from the direction IIIb. [Figure 4] 1A is a cross-sectional view of a compact of the support, functional layer, solid electrolyte and constrained layer, FIG. 1B is a cross-sectional view of the laminate, and FIG. 1C is a cross-sectional view of the sintered body. [Diagram 5] 13A is a cross-sectional view of a cell with a separator in a modified example, and FIG. 13B is a bottom view of the cell with a separator as viewed from the Vb direction. [Figure 6]FIG. 1 is a block diagram of a hydrogen production device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a perspective view of an electrochemical stack 10 in one embodiment. The electrochemical stack 10 is exemplified by a solid oxide fuel cell (SOFC) or a solid oxide hydrogen production device. The hydrogen production device is exemplified by one including a steam electrolysis cell (SOEC).

[0020] The electrochemical stack 10 includes rectangular reaction units 11, a plurality of which are stacked in the thickness direction, and rectangular end plates 12 and 13 which sandwich the reaction units 11 in the thickness direction. Bolts 14 are disposed at the four corners of the periphery of the electrochemical stack 10, penetrating the reaction units 11 and the end plates 12 and 13 in the thickness direction. The reaction units 11 and the end plates 12 and 13 are fastened together by the bolts 14.

[0021] The four spaces that penetrate the periphery of the electrochemical stack 10 in the thickness direction function as a passage 15a through which gas enters from outside the electrochemical stack 10 to a fuel chamber 33 (described later) of the reaction unit 11, a passage 15b through which gas exits from the fuel chamber 33 to the outside of the electrochemical stack 10, a passage 15c through which gas enters from outside the electrochemical stack 10 to an air chamber 35 (described later) of the reaction unit 11, and a passage 15d through which gas exits from the air chamber 35 to the outside of the electrochemical stack 10.

[0022] FIG. 2 is an exploded view of the electrochemical stack 10 cut along line II-II in FIG. 1, which passes through passages 15a and 15b. FIG. 2 is a cross-sectional view along line II-II, in which components constituting one reaction unit 11 are separated in the thickness direction. In FIG. 2, the thickness of each part is exaggerated (the same applies to FIGS. 3 to 5). The reaction unit 11 includes, in order in the thickness direction, an interconnector 16, an anode frame 17, a separator-equipped cell 18, and an air electrode frame 19. The separator-equipped cell 18 includes an electrochemical cell 20 and a separator 30 disposed in the electrochemical cell 20. Holes (passages 15a and 15b) penetrate the interconnector 16, the anode frame 17, the separator 30, and the air electrode frame 19.

[0023] The electrochemical cell 20 includes, in that order, an anode 21, a solid electrolyte 24, and an air electrode 29. The anode 21 includes a support 22 and a functional layer 23 disposed on the entire surface 22a of the support 22. The anode 21 is a rectangular, flat, porous body having higher gas permeability, with the porosity of the support 22 being higher than the porosity of the functional layer 23. The thickness of the support 22 is, for example, in the range of 200 μm to 1000 μm.

[0024] The support 22 has a constant thickness in a plane direction perpendicular to the thickness direction, except for variations due to unevenness resulting from particles constituting the support 22 and pores contained in the support 22. This makes it possible to reduce warping and waviness caused by variations in the thickness of the support 22.

[0025] The main function of the support 22 is to support the functional layer 23. The material constituting the support 22 may be the same as the material constituting the functional layer 23, or may be a material different from the material constituting the functional layer 23. When the material constituting the support 22 is different from the material constituting the functional layer 23, the material of the support 22 is exemplified by stabilized zirconia.

[0026] In a fuel cell, the functional layer 23 has a function of reacting oxide ions supplied from the solid electrolyte 24 with a fuel gas (hydrogen, carbon monoxide, hydrocarbon, etc.) to generate electrons, and in steam electrolysis, has a function of electrolyzing water vapor by passing an electric current through it to convert it into hydrogen and oxide ions. The thickness of the functional layer 23 is, for example, 10 μm to 40 μm.

[0027] The functional layer 23 includes a catalyst containing Ni and zirconia with Y dissolved therein. Examples of the catalyst include Ni, Ni-based alloys, and cermets, which are composites (sintered bodies) of NiO and oxides (solid electrolytes). In the cermets, Ni is produced by hydrogen reduction of NiO. Examples of the oxides (solid electrolytes) contained in the cermets include zirconia with Y dissolved therein. The functional layer 23 is not limited thereto, and may include, for example, a catalyst containing Ni and ceria with Gd dissolved therein.

[0028] The solid electrolyte 24 is a plate-like member that exhibits oxide ion conductivity under the operating conditions of the electrochemical cell 20. The functional layer 23 of the anode 21 is disposed over the entire back surface 24b of the solid electrolyte 24. The porosity of the solid electrolyte 24 is lower than that of the anode 21.

[0029] The solid electrolyte 24 is exemplified by stabilized zirconia, ceria-based solid solution, and solid solution of one or more selected from stabilized zirconia and ceria-based solid solution and alumina. Examples of stabilizers for stabilized zirconia include CaO, MgO, Y2O3, Sc2O3, and Yb2O3. Examples of elements dissolved in ceria in the ceria-based solid solution include Gd, Sm, and Y. The thickness of the solid electrolyte 24 is, for example, 5 μm to 40 μm.

[0030] The fuel electrode 21 includes a constraining layer 25 disposed on the back surface 22b of the support 22. In this embodiment, the constraining layer 25 includes a first layer 26 in contact with the support 22 and a second layer 27 overlapping the first layer 26. The fuel electrode 21 provided with the constraining layer 25 and the solid electrolyte 24 are a plate-shaped sintered body 28.

[0031] The air electrode 29 is disposed at the center of the surface 24a of the solid electrolyte 24. In a fuel cell, the air electrode 29 is the site where a gas-phase oxidant (oxygen) reacts with electrons to become oxide ions, and in steam electrolysis, it is the site where oxide ions release electrons to become oxygen. The air electrode 29 must be able to easily adsorb gas and must have high oxygen ion conductivity, and it must also have electronic conductivity.

[0032] The material of the cathode 29 is a perovskite oxide called La 1-X Sr X MnO 3-δ ,La 1-X Sr X Chief of Staff 3-δ ,La 1-X Sr X Co 1-Y Fe Y O 3-δ ,Pr 1-X Sr X MnO 3-δ Examples of the material for the air electrode 29 include a composite material of one or more oxides selected from these perovskite oxides and a solid electrolyte that can constitute the solid electrolyte 24.

[0033] The separator 30 is a rectangular frame-shaped member having an opening 31 larger than the air electrode 29. The material of the separator 30 is, for example, stainless steel. The separator 30 is airtightly joined to the surface 24a of the solid electrolyte 24 by brazing material or the like, avoiding the air electrode 29.

[0034] The interconnectors 16 are conductive rectangular plate-like members arranged on both sides in the thickness direction of the electrochemical cell 20. The interconnectors 16 electrically connect the reaction units 11 adjacent to each other in the thickness direction. An example of the material of the interconnectors 16 is stainless steel.

[0035] The fuel electrode frame 17 is a rectangular frame-shaped member disposed between the interconnector 16 and the separator 30. The material of the fuel electrode frame 17 is, for example, stainless steel. The fuel electrode frame 17 surrounds the electrochemical cell 20 and a current collector 32 provided in the center of the interconnector 16.

[0036] The current collector 32 electrically connects the portion of the anode 21 other than the constraining layer 25 to the interconnector 16. An example of the material of the current collector 32 is a gas permeable porous body made of a metal such as Ni. A fuel chamber 33 surrounded by the interconnector 16, the anode frame 17, and the separator 30 is provided inside the anode frame 17.

[0037] The air electrode frame 19 is a rectangular frame-shaped member disposed between the interconnector 16 and the separator 30. The material of the air electrode frame 19 is, for example, an insulator such as mica. The air electrode frame 19 surrounds a current collector 34 provided in the center of the interconnector 16. The current collector 34 electrically connects the air electrode 29 and the interconnector 16. In this embodiment, the current collector 34 is formed integrally with the interconnector 16, but this is not limited to this. It is of course possible for the current collector 34 to be a member separate from the interconnector 16.

[0038] An air chamber 35 surrounded by the interconnector 16, the air electrode frame 19, and a separator 30 is provided inside the air electrode frame 19. The separator 30 separates the fuel chamber 33 from the air chamber 35, and prevents the fuel gas in the fuel chamber 33 and the oxidizer gas (oxygen, air, etc.) in the air chamber 35 from mixing.

[0039] Returning to FIG. 1, the electrochemical stack 10 includes a terminal plate 52 disposed between the end plate 12 and the reaction unit 11, and a terminal plate 53 disposed between the end plate 13 and the reaction unit 11. The reaction units 11 are connected in series between the terminal plates 52, 53. The protruding portions of the terminal plates 52, 53 function as terminals. It is of course possible to omit the terminal plates 52, 53 and electrically connect the reaction units 11 to the end plates 12, 13, thereby making the end plates 12, 13 terminals of the electrochemical stack 10.

[0040] The separator-equipped cell 18 will be described with reference to FIG. 3. FIG. 3(a) is a cross-sectional view of the separator-equipped cell 18. FIG. 3(b) is a bottom view of the separator-equipped cell 18 as viewed from the IIIb direction of FIG. 3(a). The constraining layer 25 is provided in a band shape along the circumference 36 on the back surface 22b of the support 22, inside the circumference 36 of the portion where the support 22 and the functional layer 23 overlap in the thickness direction (the support 22 has the same size as the functional layer 23, so the portion where the support 22 and the functional layer 23 overlap in the thickness direction is equal to the support 22). The constraining layer 25 is annular with an inner circumference 37. In this embodiment, the constraining layer 25 is continuous over the entire circumference 36.

[0041] An example of a method for manufacturing the separator-equipped cell 18 will be described with reference to Fig. 4. Fig. 4(a) is a cross-sectional view of a compact 38 of the support 22, a compact 39 of the functional layer 23, a compact 40 of the solid electrolyte 24, and a compact 41 of the constrained layer 25.

[0042] The green bodies 38-41 are obtained by preparing a slurry by adding a plasticizer, a dispersant, a binder, etc. to the raw material powder, forming a sheet by a doctor blade method, and cutting the sheet to a predetermined size. If necessary, the slurry contains a pore-forming material. The green body 41 is obtained by overlapping the green body 42 of the first layer 26 and the green body 43 of the second layer 27. The material of the green body 42 is the slurry used to prepare the green body 39, and the material of the green body 43 is the slurry used to prepare the green body 40. The thickness of the green body 42 is the same as that of the green body 39, and the thickness of the green body 43 is the same as that of the green body 40.

[0043] The molded body 38 can be produced by extrusion molding, press molding, or injection molding, in addition to the doctor blade method. The molded bodies 39, 40, and 41 can be produced by thick film printing using a slurry coating, in addition to the doctor blade method.

[0044] 4(b) is a cross-sectional view of the laminate 44. In the first molding step, the molded bodies 39 and 40 are laminated in this order on the surface 38a of the molded body 38. At this time, the molded bodies 39 and 40 may be disposed in this order on the surface 38a of the molded body 38, or the molded bodies 39 and 40 may be laminated and disposed on the surface 38a of the molded body 38.

[0045] In the second molding step, the molded bodies 42 and 43 are stacked in this order on the back surface 38b of the molded body 38. In this case, the molded bodies 42 and 43 may be arranged in this order on the back surface 38b of the molded body 38, or the stacked molded bodies 42 and 43 may be arranged on the back surface 38b of the molded body 38. The order of the first and second molding steps does not matter. The laminate 44 is obtained by stacking the molded bodies 38-41.

[0046] FIG. 4(c) is a cross-sectional view of the sintered body 28. The sintered body 28 is obtained by firing the degreased laminate 44 in the firing step. The rate at which the laminate 44, in which the compacts 38-41 are stacked, shrinks during firing (shrinkage rate) varies for each compact. The shrinkage rate of the functional layer 23 (compact 39) is smaller than that of the support 22 (compact 38). The shrinkage rate of the solid electrolyte 24 (compact 40) is smaller than that of the support 22 (compact 38). The shrinkage rate of the constrained layer 25 (compact 41) is smaller than that of the support 22 (compact 38). The difference in shrinkage rate is determined by the type and particle size of the raw material powder, the porosity of the sintered body, etc.

[0047] Without the constraining layer 25, the sintered body would be significantly warped due to the difference in shrinkage rate between the functional layer 23 disposed on the front surface 22a of the support 22 and the support 22. Furthermore, the warping of the sintered body would be even greater due to the difference in shrinkage rate between the solid electrolyte 24 overlapping the functional layer 23 and the support 22. In contrast, the sintered body 28 has the constraining layer 25, which has a smaller shrinkage rate than the support 22, disposed on the back surface 22b of the support 22, and therefore the warping can be reduced.

[0048] The green body 41 of the constraint layer 25 includes green bodies 42 and 43. The green body 42 is made of the same material as the green body 39 of the functional layer 23, and the green body 43 is made of the same material as the green body 40 of the solid electrolyte 24. Since there is no need to separately prepare the material for the green body 41, warping of the sintered body 28 can be reduced without increasing the amount of material.

[0049] The shrinkage rate of compact 42 (constraining layer 25) is approximately the same as that of compact 39 (functional layer 23), and the shrinkage rate of compact 43 (constraining layer 25) is approximately the same as that of compact 40 (solid electrolyte 24). In laminate 44, compacts 39, 40 and compacts 42, 43, which have approximately the same shrinkage rate, are arranged symmetrically across compact 38 (support 22), so that the effect of reducing warpage of sintered body 28 can be increased.

[0050] After obtaining the sintered body 28, the green body 45 of the air electrode 29 is placed at the center of the surface 24a of the solid electrolyte 24, and a brazing material (not shown) is placed on the periphery of the surface 24a. The green body 45 is obtained by adding a plasticizer, a dispersant, a binder, etc. to the raw material powder to prepare a slurry, forming a sheet by a doctor blade method, and cutting the sheet to a predetermined size. In addition to the doctor blade method, the green body 45 can be produced by thick film printing by applying the slurry. The separator 30 is pressed against the brazing material and heated to a predetermined temperature, and the green body 45 is fired and the separator 30 is brazed at the same time. This results in a cell 18 with separator (see FIG. 3(a)).

[0051] Returning to Fig. 3, as shown in Fig. 3(a), the width D1 (see Fig. 3(b)) of the inner periphery 37 of the constraining layer 25 becomes smaller in the thickness direction of the constraining layer 25 toward the rear surface 22b of the support 22. Since the fuel gas can be easily guided to the support 22 along the inner periphery 37 of the constraining layer 25, the reaction of the fuel gas at the fuel electrode 21 increases.

[0052] As shown in Figure 3(b), constraining layer 25 is provided in an annular shape on back surface 22b of support 22, so that current collector 32 (see Figure 2) abuts on a portion of support 22 that is more inward than inner circumference 37 of constraining layer 25, allowing anode 21 to function with constraining layer 25 left in place. This makes it unnecessary to remove constraining layer 25 when operating anode 21.

[0053] Since the constraining layer 25 is continuous over the entire circumference 36, warping of the sintered body 28 can be reduced compared to when the constraining layer 25 is discontinued halfway along the circumference 36, when the constraining layer 25 is provided intermittently over the entire circumference 36, or when the constraining layer 25 is provided along part of the circumference 36. Note that the constraining layer 25 does not have to be continuous over the entire circumference 36. Even if the constraining layer 25 is not continuous, as long as the total length of the constraining layer 25 along the circumference 36 is 80% or more of the total length of the circumference 36, the warping of the sintered body 28 can be controlled within an acceptable range.

[0054] Since the outer periphery of the constraining layer 25 is at the same position as the circumference 36, warping of the portion of the sintered body 28 close to the circumference 36 can be reduced compared to the case where there is a distance in the plane between the outer periphery of the constraining layer 25 and the circumference 36. Note that, when the difference between the shrinkage rate of the functional layer 23 and the shrinkage rate of the support body 22 is small, a distance may be provided between the outer periphery of the constraining layer 25 and the circumference 36.

[0055] Since the span D1 of the inner circumference 37 of the constraining layer 25 is smaller than the length D2 in the plane direction perpendicular to the thickness direction of the air electrode 29, the constraining layer 25 includes an overlapping portion 46 where the air electrode 29 overlaps in the thickness direction. Due to the overlapping portion 46, the mechanical strength of the electrochemical cell 20 can be increased compared to an electrochemical cell in which the constraining layer 25 and the air electrode 29 do not overlap in the thickness direction. In addition, since the width of the constraining layer 25 is wider than that of an electrochemical cell in which the constraining layer 25 and the air electrode 29 do not overlap in the thickness direction, the effect of the constraining layer 25 in reducing warpage of the sintered body 28 is increased.

[0056] As the planar length D3 of the overlapping portion 46 becomes longer, the area of ​​the fuel electrode 21 becomes smaller due to the constraining layer 25, and the reaction of the fuel gas at the fuel electrode 21 decreases, so the planar length D3 of the overlapping portion 46 is preferably 24% or less of the planar length D2 of the air electrode 29. This is because this allows both the mechanical strength of the electrochemical cell 20 and the reactivity at the fuel electrode 21 to be achieved.

[0057] In the separator-equipped cell 18, the span D4 of the opening 31 of the separator 30 is larger than the span D1 of the inner periphery 37 of the constraining layer 25. Since the constraining layer 25 and the separator 30 overlap in the thickness direction, the mechanical strength of the electrochemical cell 20 near the edge can be improved. Furthermore, since the separator-equipped cell 18 has an overlapping portion 46, the mechanical strength of the electrochemical cell 20 near the edge can be further improved.

[0058] A modified example will be described with reference to Fig. 5. In the modified example, the same parts as those described in the embodiment are given the same reference numerals and the description will be omitted below. Fig. 5(a) is a cross-sectional view of a separator-equipped cell 47 in the modified example. Fig. 5(b) is a bottom view of the separator-equipped cell 47 as viewed from the Vb direction.

[0059] As shown in FIG. 5(a), the separator-equipped cell 47 includes an electrochemical cell 48 including a solid electrolyte 24 and a separator 30 attached to the surface 24a of the solid electrolyte 24. The electrochemical cell 48 includes a constraining layer 49 provided along the circumference 36 on the inner side of the circumference 36 of the portion where the functional layer 23 and the support 22 overlap in the thickness direction, on the back surface 22b of the support 22. The constraining layer 49 includes a first layer 50 in contact with the support 22 and a second layer 51 in contact with the first layer 50. The first layer 50 is made of the same material as the functional layer 23, and the second layer 51 is made of the same material as the solid electrolyte 24. The constraining layer 49 provided on the back surface 22b of the support 22 can reduce warping of the sintered body 28.

[0060] 5(b), the span D1 of the inner periphery 37 of the constraining layer 49 is larger than the length D2 in the planar direction of the air electrode 29, so that the constraining layer 49 is located outside the portion where the air electrode 29 overlaps in the thickness direction. Compared to an electrochemical cell in which the air electrode 29 and the constraining layer 49 overlap in the thickness direction, the constraining layer 49 can prevent the area of ​​the anode 21 from becoming smaller, so that the reactivity of the anode 21 can be ensured.

[0061] A hydrogen production device 60 including an electrochemical stack 10 and a hot module 61 will be described with reference to Fig. 6. Fig. 6 is a block diagram of the hydrogen production device 60. The hydrogen production device 60 is a device that produces hydrogen from water and includes a hot module 61.

[0062] The hot module 61 includes the electrochemical stack 10, a vaporizer 62 that generates water vapor to be supplied to the electrochemical stack 10, a heat exchanger 63 that exchanges heat between the gas supplied to the electrochemical stack 10 and the gas generated by the electrochemical stack 10, and a heater 64 that heats the electrochemical stack 10. In the hot module 61, the electrochemical stack 10, the vaporizer 62, the heat exchanger 63, and the heater 64 are disposed inside a thermal insulation material 65 in order to reduce heat radiation.

[0063] The vaporizer 62 includes a heat exchanger that exchanges heat with high-temperature gas containing oxygen generated by the electrochemical stack 10, and heats water to produce water vapor. The water vapor generated by the vaporizer 62 contains hydrogen that reduces oxidation of the catalyst contained in the anode 21. The hydrogen-containing water vapor exchanges heat with hydrogen and oxygen generated by the electrochemical stack 10 by the heat exchanger 63, is heated to the operating temperature of the electrochemical stack 10 by the heater 64, and is supplied to the fuel chamber 33 of the electrochemical stack 10. The air exchanges heat with hydrogen and oxygen generated by the electrochemical stack 10 by the heat exchanger 63, is heated to the operating temperature of the electrochemical stack 10 by the heater 64, and is supplied to the air chamber 35 of the electrochemical stack 10.

[0064] Examples of the heat insulating material 65 include heat resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), and a heat resistant container made of heat resistant fibers. The heat resistant fibers fill the gaps between the electrochemical stack 10, the vaporizer 62, the heat exchanger 63, and the heater 64. The condenser 66 is a device that cools the hydrogen gas, and liquefied water is supplied to the vaporizer 62 as raw water.

[0065] The present invention has been described above based on an embodiment, but the present invention is not limited to the above embodiment, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0066] In the embodiment, the constraining layer 25, 49 is described as being made up of a plurality of layers including the first layer 26, 50 and the second layer 27, 51, but this is not necessarily limited to this. Of course, the constraining layer 25, 49 can be a single layer.

[0067] In the embodiment, the constraining layer 25,49 includes the first layer 26,50 made of the same material as the functional layer 23 and the second layer 27,51 made of the same material as the solid electrolyte 24, but this is not necessarily limited to this. It is possible to omit either the first layer 26,50 or the second layer 27,51. This is because the shrinkage rate of both the first layer 26,50 and the second layer 27,51 is smaller than the shrinkage rate of the support 22, and therefore, by providing either the first layer 26,50 or the second layer 27,51 as the constraining layer 25,49, the warping of the sintered body 28 can be reduced.

[0068] In the embodiment, the first layers 26, 50 of the constraining layers 25, 49 have the same thickness as the functional layer 23, and the second layers 27, 51 have the same thickness as the solid electrolyte 24, but this is not necessarily limited to the above. The thicknesses of the constraining layers 25, 49 can be appropriately set so as to reduce warping of the sintered body 28.

[0069] In the embodiment, the constraining layers 25, 49 contain the same material as the functional layer 23 and the solid electrolyte 24, but this is not necessarily limited to this. Since the constraining layers 25, 49 only need to have a smaller shrinkage rate than the support 22, the constraining layers 25, 49 can be made using a material different from the materials of the functional layer 23 and the solid electrolyte 24.

[0070] In the embodiment, the electrochemical cells 20, 48 and the separator-attached cells 18, 47 including the constraining layers 25, 49 arranged on the back surface 22b of the support 22 have been described, but the present invention is not necessarily limited to this. After obtaining the electrochemical cells 20, 48, the separator-attached cells 18, 47, and the sintered body 28, it is of course possible to remove the constraining layers 25, 49. This is because the constraining layers 25, 49 are intended to reduce warping of the support 22 due to heating, and therefore the constraining layers 25, 49 may be removed once application of heat sufficient to cause warping is no longer present.

[0071] In the embodiment, the sintered body 28 in which the fuel electrode 21 and the solid electrolyte 24 are integrated is produced by firing the laminate 44, but this is not necessarily limited to this. It is of course possible to produce the fuel electrode 21 and the solid electrolyte 24 separately by firing and then bond them to produce the electrochemical cell 20, 48. In this case as well, the constraining layer 25, 49 is provided on the back surface 22b of the support 22 of the fuel electrode 21, so that warping of the fuel electrode 21 can be reduced.

[0072] Although not described in the embodiment, it is of course possible to dispose an intermediate layer between the solid electrolyte 24 and the air electrode 29. The intermediate layer reduces reaction between the solid electrolyte 24 and the air electrode 29 at high temperatures during heating when the separator-equipped cells 18, 47 are fabricated or during operation of the electrochemical cells 20, 48. Examples of materials for the intermediate layer include ceria-based solid solutions. Examples of elements that dissolve in ceria in ceria-based solid solutions include Gd, Sm, La, and Y. [Explanation of symbols]

[0073] 10 Electrochemical Stack 18,47 Cell with separator 20,48 Electrochemical Cell 21 Fuel electrode 22 Support 22a surface 22b Back side 23 Functional Layer 24 Solid electrolyte 24a surface 24b back side 25,49 restraint layer 28 Sintered body 29 Air electrode 30 Separator 31 Aperture 36 laps 37 Inner Circumference 38 Support body 38a surface 38b Back 39 Functional layer molding 41 Constraint layer molding 44 Laminate 46 Overlap 60 Hydrogen production equipment 61 Hot Module 62 Carburetor 63 Heat exchanger 64 Heater 65 Insulation

Claims

1. A fuel electrode for a solid oxide electrochemical cell, comprising a sintered body including a support and a functional layer disposed on a surface of the support and having a porosity lower than that of the support, a constraint layer disposed on a back surface of the support along a periphery inside a periphery of a portion where the functional layer and the support overlap in a thickness direction; The fuel electrode has a smaller shrinkage rate during firing of the constraining layer than a shrinkage rate during firing of the support.

2. 2. The fuel electrode according to claim 1, wherein the inner circumference of the constraining layer has a diameter that decreases in the thickness direction of the constraining layer toward the rear surface of the support.

3. A solid oxide electrochemical cell comprising a solid electrolyte and a fuel electrode disposed on a back surface of the solid electrolyte, The fuel electrode comprises the fuel electrode according to claim 1 or 2, The sintered body is an electrochemical cell including, in this order from the front surface to the back surface, the solid electrolyte, the functional layer, the support, and the constraining layer.

4. Further comprising an air electrode disposed on a surface of the solid electrolyte, 4. The electrochemical cell in accordance with claim 3, wherein the constraining layer includes an overlapping portion where the air electrode overlaps in a thickness direction.

5. 5. The electrochemical cell in accordance with claim 4, wherein the length of the overlapping portion in a planar direction perpendicular to the thickness direction is 24% or less of the length of the air electrode in the planar direction.

6. Further comprising an air electrode disposed on a surface of the solid electrolyte, 4. The electrochemical cell according to claim 3, wherein the constraining layer is positioned outside the portion where the air electrode overlaps in the thickness direction.

7. The electrochemical cell of claim 3; A separator having a center opening and disposed on the solid electrolyte, A separator-equipped cell, wherein the diameter of the opening of the separator is greater than the diameter of the inner circumference of the constraining layer.

8. An electrochemical stack comprising a plurality of electrochemical cells according to claim 3 stacked together.

9. An electrochemical stack according to claim 8; a vaporizer that generates water vapor that is supplied to the electrochemical stack; a heat exchanger for exchanging heat with the gas supplied to the electrochemical stack; a heater for heating the electrochemical stack; a hot module comprising an insulation material within which the electrochemical stack, the vaporizer, the heat exchanger and the heater are disposed.

10. A hydrogen production device comprising the hot module according to claim 9.

11. A method for producing an anode for a solid oxide electrochemical cell, comprising: a sintered body including a support; and a functional layer disposed on a surface of the support and having a lower porosity than the porosity of the support, the method comprising the steps of: a first molding step of laminating a molded body of the functional layer on a surface of the molded body of the support; a second molding step of obtaining a laminate in which a molded body of a constraining layer is disposed on the back surface of the molded body of the support along the inner periphery of a portion where the molded body of the functional layer overlaps in the thickness direction; A firing step of firing the laminate, A method for manufacturing an anode, wherein the constraining layer has a smaller shrinkage rate during firing than the support body.

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