Electrochemical cell

Abstract

An electrolytic cell (1) is provided with a metal support (10) and a cell body (20). The cell body (20) has a hydrogen electrode layer (6) covering each communication hole (11) formed on a first main surface (12) of the metal support (10). The hydrogen electrode layer (6) has a first region (61) within 5 μm in the thickness direction from a first surface (S1) in contact with the metal support (10), a second region (62) within 5 μm in the thickness direction from a second surface (S2) in contact with an electrolyte layer (7) and a third region (63) between the first region (61) and the second region (62). The first region (61), the second region (62) and the third region (63) each contain nickel and an oxide ion conductive material. The nickel content in the first region (61) is lower than the nickel content in the third region (63).

Description

Technical Field

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

Background Art

[0002] Conventionally, an electrochemical cell (such as an electrolytic cell or a fuel cell) including a cell main body disposed on a metal support has been known (see, for example, Patent Document 1).

[0003] The metal support has a plurality of communication holes formed in a main surface. The cell main body is formed on the main surface of the metal support and has a first electrode layer covering the plurality of communication holes, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer. The first electrode layer contains nickel as a metal for imparting conductivity. Nickel contained in the first electrode layer becomes nickel oxide in an oxidizing atmosphere and metallic nickel in a reducing atmosphere.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-described electrochemical cell, the first electrode layer expands / contracts due to an oxidation-reduction cycle. Specifically, when the first electrode layer is reduced before the operation of the electrochemical cell, nickel oxide becomes metallic nickel and the first electrode layer contracts. When the operation of the electrochemical cell stops and the first electrode layer changes from a reducing atmosphere to an oxidizing atmosphere, metallic nickel becomes nickel oxide and the first electrode layer expands.

[0006] Thus, when the first electrode layer expands / contracts due to an oxidation-reduction cycle, the first electrode layer may peel off from the metal support.

[0007] An object of the present invention is to provide an electrochemical cell capable of suppressing peeling of a first electrode layer from a metal support.

Means for Solving the Problems

[0008] The electrochemical cell according to the first aspect of the present invention includes a metal support having a plurality of communication holes formed on a main surface, a first electrode layer formed on the main surface and covering the plurality of communication holes, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer. The cell main body portion. The first electrode layer has a first region within 5 μm in the thickness direction from the first surface in contact with the metal support, a second region within 5 μm in the thickness direction from the second surface in contact with the electrolyte layer, and a third region between the first region and the second region. Each of the first region, the second region, and the third region contains nickel and an oxide ion conductive material. The nickel content in the first region is lower than the nickel content in the third region.

[0009] The electrochemical cell according to the second aspect of the present invention pertains to the above first aspect, and the nickel content in the second region is lower than the nickel content in the third region.

[0010] The electrochemical cell according to the third aspect of the present invention pertains to the above first or second aspect, and the nickel content in the second region is lower than the nickel content in the first region.

[0011] The electrochemical cell according to the fourth aspect of the present invention pertains to the above first to fourth aspects, and the first electrode layer has a fourth region disposed inside at least one of the plurality of communication holes. The fourth region contains nickel and an oxide ion conductive material. The nickel content in the fourth region is lower than the nickel content in the third region.

Effects of the Invention

[0012] According to the present invention, it is possible to provide an electrochemical cell capable of suppressing peeling of the first electrode layer from the metal support.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0014] (Electrolytic cell 1) Figure 1 is a plan view of the electrolytic cell 1 according to the embodiment. Figure 2 is a cross-sectional view taken along line A-A of Figure 1. The electrolytic cell 1 is an example of the "electrochemical cell" according to the present invention.

[0015] The electrolytic cell 1 is formed in a plate shape that spreads in the X-axis direction and the Y-axis direction. In the present embodiment, when viewed in plan from the Z-axis direction perpendicular to the X-axis direction and the Y-axis direction, the electrolytic cell 1 is formed in a rectangle extending in the Y-axis direction. However, the planar shape of the electrolytic cell 1 is not particularly limited, and it may be a polygon other than a rectangle, an ellipse, a circle, or the like. Note that each of the X-axis direction and the Y-axis direction is the surface direction of the electrolytic cell 1, and the Z-axis direction is the thickness direction of the electrolytic cell 1.

[0016] As shown in Figure 2, the electrolytic cell 1 includes a metal support 10, a cell main body 20, and a flow path member 30.

[0017] [Metal support 10] The metal support 10 supports the cell main body 20. The metal support 10 is formed in a plate shape. The metal support 10 may be flat or curved.

[0018] The metal support 10 only needs to be able to support the electrolytic cell 1, and its thickness is not particularly limited, but for example, it can be 0.1 mm or more and 2.0 mm or less.

[0019] As shown in FIG. 2, the metal support 10 has a plurality of communication holes 11, a first main surface 12, and a second main surface 13.

[0020] Each communication hole 11 penetrates the metal support 10 from the first main surface 12 to the second main surface 13. Each communication hole 11 opens to each of the first main surface 12 and the second main surface 13. The opening of each communication hole 11 on the first main surface 12 side is covered by the hydrogen electrode layer 6. The opening of each communication hole 11 on the second main surface 13 side is connected to a flow path 30a described later.

[0021] Each communication hole 11 can be formed by machining (for example, punching), laser processing, or chemical processing (for example, etching).

[0022] In the present embodiment, each communication hole 11 is linearly formed along the Z-axis direction. However, each communication hole 11 may be inclined with respect to the Z-axis direction, or may not be linear. Also, the communication holes 11 may be connected to each other.

[0023] The first main surface 12 is provided on the opposite side of the second main surface 13. The cell main body 20 is disposed on the first main surface 12. The flow path member 30 is joined to the second main surface 13.

[0024] The metal support 10 is made of a metal material. For example, the metal support 10 is made of an alloy material containing Cr (chromium). Examples of such metal materials include Fe-Cr alloy steel (such as stainless steel) and Ni-Cr alloy steel. The content rate of Cr in the metal support 10 is not particularly limited, but can be 4 mass% or more and 30 mass% or less.

[0025] The metal support 10 may contain Ti (titanium) or Zr (zirconium). The content rate of Ti in the metal support 10 is not particularly limited, but can be 0.01 mol% or more and 1.0 mol% or less. The content rate of Al in the metal support 10 is not particularly limited, but can be 0.01 mol% or more and 0.4 mol% or less. The metal support 10 contains Ti as TiO 2It may be contained as [titania], or Zr may be contained as ZrO 2 (zirconia).

[0026] The metal support 10 may have an oxide film formed on its surface by oxidation of the constituent elements of the metal support 10. As the oxide film, for example, a chromium oxide film is typical. The chromium oxide film covers at least a part of the surface of the metal support 10. Further, the chromium oxide film may cover at least a part of the inner wall surface of each communication hole 11.

[0027] [Cell main body 20] The cell main body 20 is disposed on the metal support 10. The cell main body 20 is supported by the metal support 10. The cell main body 20 has a hydrogen electrode layer 6 (cathode), an electrolyte layer 7, a reaction prevention layer 8, and an oxygen electrode layer 9 (anode).

[0028] The hydrogen electrode layer 6, the electrolyte layer 7, the reaction prevention layer 8, and the oxygen electrode layer 9 are laminated in this order from the side of the metal support 10 in the Z-axis direction. The hydrogen electrode layer 6, the electrolyte layer 7, and the oxygen electrode layer 9 are essential components, and the reaction prevention layer 8 is an optional component.

[0029] [Hydrogen electrode layer 6] The hydrogen electrode layer 6 is an example of the "first electrode layer" according to the present invention. The hydrogen electrode layer 6 is disposed between the metal support 10 and the electrolyte layer 7. The hydrogen electrode layer 6 is formed on the first main surface 12 of the metal support 10. In the present embodiment, a part of the hydrogen electrode layer 6 is disposed inside each communication hole 11 of the metal support 10. The detailed configuration of the hydrogen electrode layer 6 will be described later.

[0030] The raw material gas is supplied to the hydrogen electrode layer 6 through each communication hole 11. The raw material gas contains at least H 2 O.

[0031] When the raw material gas contains only H 2 O, the hydrogen electrode layer 6 generates H 2 from the raw material gas according to the electrochemical reaction of water electrolysis represented by the following formula (1).

[0032] · Hydrogen electrode layer 6: H 2 O + 2e - → H 2 + O 2- ···(1)

[0033] When the raw material gas contains CO in addition to H 2 O, the hydrogen electrode layer 6 generates H 2 , CO and O 2 from the raw material gas according to the electrochemical reactions of co - electrolysis shown in the following formulas (2), (3), and (4). 2-

[0034] · Hydrogen electrode layer 6: CO 2 + H 2 O + 4e - → CO + H 2 + 2O 2- ···(2) · Electrochemical reaction of H 2 O: H 2 O + 2e - → H 2 + O 2- ···(3) · Electrochemical reaction of CO 2 : CO 2 + 2e - → CO + O 2- ···(4)

[0035] The hydrogen electrode layer 6 is a porous body having electron conductivity. The hydrogen electrode layer 6 contains nickel (Ni) and an oxide ion conductive material.

[0036] Ni functions as an electron - conducting substance. In the case of co - electrolysis, Ni also functions as a thermal catalyst that promotes the thermal reaction between the generated H 2 and CO 2 contained in the raw material gas to maintain an appropriate gas composition for methanation and the reverse water - gas shift reaction, etc.

[0037] ​Ni exists in the state of nickel oxide (NiO) in an oxidizing atmosphere and in the state of metallic Ni in a reducing atmosphere. The hydrogen electrode layer 6 is exposed to an oxidizing atmosphere during the stoppage of the electrolytic cell 1 and to a reducing atmosphere during the operation of the electrolytic cell 1 and during the reduction treatment carried out before the operation of the electrolytic cell 1. The hydrogen electrode layer 6 expands / contracts with the oxidation / reduction of Ni.

[0038] As the oxide ion conductive material, YSZ, CSZ, ScSZ, GDC, SDC, (La,Sr)(Cr,Mn)O 3 , (La,Sr)TiO 3 , Sr 2 (Fe,Mo) 2 O 6 , (La,Sr)VO 3 , (La,Sr)FeO 3 , LDC (lanthanum-doped ceria), LSGM (lanthanum gallate), and a mixed material obtained by combining two or more of these can be used.

[0039] The thickness of the hydrogen electrode layer 6 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0040] The method for forming the hydrogen electrode layer 6 is not particularly limited, and a firing method, a spray coating method (such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (such as a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. can be used.

[0041] [Electrolyte layer 7] The electrolyte layer 7 is disposed between the hydrogen electrode layer 6 and the oxygen electrode layer 9. In the present embodiment, since the reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the electrolyte layer 7 is sandwiched between the hydrogen electrode layer 6 and the reaction prevention layer 8.

[0042] The electrolyte layer 7 covers the hydrogen electrode layer 6 and covers the region of the first main surface 12 of the metal support 10 that is exposed from the hydrogen electrode layer 6.

[0043] The electrolyte layer 7 transmits the O 2- generated in the hydrogen electrode layer 6 to the oxygen electrode layer 9 side. The electrolyte layer 7 is composed of a dense material having oxide ion conductivity. The electrolyte layer 7 can be composed of, for example, YSZ (yttria-stabilized zirconia, such as 8YSZ), GDC (gadolinium-doped ceria), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), LSGM (lanthanum gallate), etc.

[0044] The porosity of the electrolyte layer 7 is not particularly limited, but can be, for example, 0.1% or more and 7% or less. The thickness of the electrolyte layer 7 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0045] The method for forming the electrolyte layer 7 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, etc. can be used.

[0046] [Reaction prevention layer 8] The reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9. The reaction prevention layer 8 is disposed on the opposite side of the hydrogen electrode layer 6 with respect to the electrolyte layer 7. The reaction prevention layer 8 suppresses the formation of a layer with high electrical resistance due to the reaction of the constituent elements of the electrolyte layer 7 with the constituent elements of the oxygen electrode layer 9.

[0047] The reaction prevention layer 8 is composed of an oxide ion conductive material. The reaction prevention layer 8 can be composed of GDC, SDC, etc.

[0048] The porosity of the reaction prevention layer 8 is not particularly limited, but can be, for example, 0.1% or more and 50% or less. The thickness of the reaction prevention layer 8 is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0049] The method for forming the reaction prevention layer 8 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, etc. can be used.

[0050] [Oxygen electrode layer 9] The oxygen electrode layer 9 is an example of the "second electrode layer" according to the present invention. The oxygen electrode layer 9 is disposed on the opposite side of the hydrogen electrode layer 6 with respect to the electrolyte layer 7. In the present embodiment, since the reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the oxygen electrode layer 9 is connected to the reaction prevention layer 8. When the reaction prevention layer 8 is not disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the oxygen electrode layer 9 is connected to the electrolyte layer 7.

[0051] The oxygen electrode layer 9 generates O 2- from O 2 transmitted from the hydrogen electrode layer 6 through the electrolyte layer 7 according to the chemical reaction of the following formula (2).

[0052] · Oxygen electrode layer 9: 2O 2- → O 2 + 4e - ···(2)

[0053] The oxygen electrode layer 9 is composed of a porous material having oxide ion conductivity and electron conductivity. The oxygen electrode layer 9 can be composed of, for example, a composite material of one or more of (La, Sr)(Co, Fe)O 3 , (La, Sr)FeO 3 , La(Ni, Fe)O 3 , (La, Sr)CoO 3 , and (Sm, Sr)CoO 3 and an oxide ion conductive material (such as GDC).

[0054] The porosity of the oxygen electrode layer 9 is not particularly limited, but can be, for example, 20% or more and 60% or less. The thickness of the oxygen electrode layer 9 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0055] The method for forming the oxygen electrode layer 9 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0056] [Flow path member 30] The flow path member 30 is joined to the second main surface 13 of the metal support 10. The flow path member 30 forms a flow path 30a between itself and the metal support 10. A raw material gas is supplied to the flow path 30a. The raw material gas supplied to the flow path 30a is supplied to the hydrogen electrode layer 6 of the cell main body 20 through each communication hole 11 of the metal support 10.

[0057] The flow path member 30 can be formed of, for example, an alloy material. The flow path member 30 may be formed of the same material as the metal support 10. In this case, the flow path member 30 may be substantially integral with the metal support 10.

[0058] The flow path member 30 has a frame body 31 and an interconnector 32. The frame body 31 is an annular member that surrounds the side of the flow path 30a. The frame body 31 is joined to the second main surface 13 of the metal support 10. The interconnector 32 is a plate-like member for electrically connecting the external power source or another electrolytic cell to the electrolytic cell 1 in series. The interconnector 32 is joined to the frame body 31.

[0059] In the present embodiment, the frame body 31 and the interconnector 32 are separate members, but the frame body 31 and the interconnector 32 may be an integral member.

[0060] (Configuration of the hydrogen electrode layer 6) FIG. 3 is a partially enlarged view of FIG. 2. As shown in FIG. 3, the hydrogen electrode layer 6 has a first region 61, a second region 62, a third region 63, and a fourth region 64.

[0061] The first region 61 is a region within 5 μm in the Z-axis direction (thickness direction) from the first surface S1 that contacts the metal support 10 among the hydrogen electrode layer 6. The second region 62 is a region within 5 μm in the Z-axis direction from the second surface S2 that contacts the electrolyte layer 7 among the hydrogen electrode layer 6. The third region 63 is a region between the first region 61 and the second region 62 among the hydrogen electrode layer 6. The fourth region 64 is a region disposed inside the communication hole 11 of the metal support 10 among the hydrogen electrode layer 6. By locking the fourth region 64 to the communication hole 11, an anchor effect on the metal support 10 is exhibited.

[0062] The first to third regions 61 to 63 are essential components, and the fourth region 64 is an optional component. The fourth region 64 only needs to exist inside at least one of the plurality of communication holes 11 formed in the metal support 10. Therefore, the number of the fourth regions 64 may be the same as the number of the communication holes 11 or may be less than the number of the communication holes 11.

[0063] The first surface S1 of the hydrogen electrode layer 6 contacts the first main surface 12 of the metal support 10. When specifying the first region 61, in the cross section along the Z-axis direction, the approximate straight line of the first surface S1 obtained by the least squares method is used. Specifically, the region of the surface of the hydrogen electrode layer 6 that contacts the first main surface 12 of the metal support 10 is approximated by a straight line using the least squares method, and the obtained approximate straight line is taken as the first surface S1 of the hydrogen electrode layer 6. Note that the inner peripheral surface of the communication hole 11 of the metal support 10 is not included in the region of the surface of the hydrogen electrode layer 6 that contacts the first main surface 12 of the metal support 10.

[0064] The second surface S2 of the hydrogen electrode layer 6 contacts the hydrogen electrode layer side surface S3 of the electrolyte layer 7. When specifying the second region 62, in the cross section along the Z-axis direction, the approximate straight line of the second surface S2 obtained by the least squares method is used. Specifically, the region of the surface of the hydrogen electrode layer 6 that contacts the hydrogen electrode layer side surface S3 of the electrolyte layer 7 is approximated by a straight line using the least squares method, and the obtained approximate straight line is taken as the second surface S2 of the hydrogen electrode layer 6.

[0065] Each of the first to fourth regions 61 to 64 contains Ni and an oxide ion conductive material.

[0066] The content rate of Ni in the first region 61 is lower than the content rate of Ni in the third region 63. Thereby, since the expansion / contraction of the first region 61 caused by the oxidation-reduction cycle can be reduced, peeling of the hydrogen electrode layer 6 from the metal support 10 can be suppressed. Further, in the third region 63, the electron conductivity and the catalytic performance can be improved. Therefore, it is possible to achieve both suppression of peeling of the hydrogen electrode layer 6 and maintenance of the electrode performance.

[0067] The Ni content in the second region 62 is preferably lower than the Ni content in the third region 63. By doing so, expansion / contraction can be reduced not only in the first region 61 but also in the second region 62, so that it is possible to achieve both suppression of an increase in internal resistance associated with deterioration of the adhesion between the hydrogen electrode layer 6 and the electrolyte layer 7 when the redox cycle is repeated and maintenance of the electrode performance.

[0068] The Ni content in the second region 62 is preferably lower than the Ni content in the first region 61. As a result, the reduction shrinkage amount of the second region 62 becomes smaller than that of the first region 61, so that the shrinkage balance in the entire hydrogen electrode layer 6 can be improved. As a result, it is possible to suppress the hydrogen electrode layer 6 from warping convexly toward the metal support 10 side, and thus it is possible to suppress the hydrogen electrode layer 6 (particularly, the outer peripheral portion of the hydrogen electrode layer 6 in the plane direction) from peeling off from the metal support 10.

[0069] The Ni content in the fourth region 64 is preferably lower than the Ni content in the third region 63. By doing so, expansion / contraction of the fourth region 64 due to the redox cycle can be reduced, so that it is possible to suppress a change in the shape of the fourth region 64. As a result, the anchor effect by the fourth region 64 can be maintained.

[0070] The Ni contents in the first to fourth regions 61 to 64 are calculated by the same method as described below.

[0071] The Ni content in the first region 61 is calculated by measuring the Ni content at five randomly selected locations (random selection) spaced apart in the plane direction at the center in the thickness direction of the first region 61 in the cross section of the hydrogen electrode layer 6 along the Z-axis direction, and calculating the arithmetic mean of the five obtained measurement values. The value of the Ni content in the first region 61 is not particularly limited, but can be 25 mol% or more and 45 mol% or less.

[0072] The Ni content in the second region 62 is calculated by measuring the Ni content at five randomly selected points in the plane direction at the center in the thickness direction of the second region 62 in the cross-section of the hydrogen electrode layer 6 along the Z-axis direction, and calculating the arithmetic mean of the five obtained measurement values. The value of the Ni content in the second region 62 is not particularly limited, but can be 20 mol% or more and 45 mol% or less.

[0073] The Ni content in the third region 63 is calculated by measuring the Ni content at four points that divide the third region 63 into five equal parts in the Z-axis direction in the cross-section of the hydrogen electrode layer 6 along the Z-axis direction, and calculating the arithmetic mean of the four obtained measurement values. The value of the Ni content in the third region 63 is not particularly limited, but can be 30 mol% or more and 50 mol% or less.

[0074] The Ni content in the fourth region 64 is calculated by measuring the Ni content at five randomly selected points in the plane direction at the center in the thickness direction of the fourth region 64 in the cross-section of the hydrogen electrode layer 6 along the Z-axis direction, and calculating the arithmetic mean of the five obtained measurement values. The value of the Ni content in the fourth region 64 is not particularly limited, but can be 20 mol% or more and 45 mol% or less.

[0075] Note that the Ni content is calculated by the following method. First, using an SEM device (manufactured by JEOL Ltd., FE-SEM JSM-7900F) and an EDS device (JED-2300) attached to the SEM device, a composition mapping image of Ni on the cross-section is acquired at a magnification of 5000 to 10000 times. Next, using image analysis software Image-Pro manufactured by MEDIACYBERNETICS, the Ni particle portion is specified in the Ni composition mapping image by performing binarization processing in image analysis. Then, the Ni content is calculated by dividing the total area of the Ni particle portion by the total area of the backscattered electron image.

[0076] (Modification of the embodiment) As described above, embodiments of the present invention have been explained. However, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention.

[0077] [Modification Example 1] In the above embodiment, when the first main surface 12 of the metal support 10 is planar (that is, linear in a cross section along the Z-axis direction as shown in FIG. 3), the first surface S1 of the hydrogen electrode layer 6 is specified by the first main surface 12 of the metal support 10.

[0078] However, when the first main surface 12 of the metal support 10 is not planar (for example, when the metal support 10 is made of a porous metal), it is difficult to specify the first surface S1 of the hydrogen electrode layer 6 by the first main surface 12 of the metal support 10.

[0079] Therefore, a method for specifying the first surface S1 of the hydrogen electrode layer 6 when the first main surface 12 of the metal support 10 is not planar will be described with reference to FIG. 4. FIG. 4 is a cross section along the Z-axis direction (thickness direction) of the electrolytic cell 100.

[0080] The electrolytic cell 100 has the same configuration as the electrolytic cell 1 according to the above embodiment, except that the metal support 110 is made of a porous metal. The metal support 110 has metal particles 111 connected in a three-dimensional network and a plurality of communication holes 112 connected to each other. The first main surface 113 of the metal support 10 has irregularities formed along the outer edge of the metal particles 111.

[0081] In the electrolytic cell 100, first, the second surface S2 of the hydrogen electrode layer 6 is specified by the hydrogen electrode layer-side surface S3 of the electrolyte layer 7. Next, when the second surface S2 of the hydrogen electrode layer 6 is horizontally moved in the Z-axis direction toward the metal support 110, the intersection points P that intersect the metal particles 111 are specified. At this time, the intersection points P are specified for each lump of the metal particles 111 that are separated on the cross section. In the example shown in FIG. 4, since the metal particles 111 are divided into three lumps, the intersection points P1 to P3 are specified in FIG. 4. Finally, the line connecting the intersection points P1 to P3 in sequence with a straight line is taken as the first surface S1 of the hydrogen electrode layer 6.

[0082] As described above, when the first main surface 113 of the metal support 110 is not planar, the first surface S1 of the hydrogen electrode layer 6 can be specified based on the surface S3 on the hydrogen electrode layer side of the electrolyte layer 7.

[0083] [Modification Example 2] In the above embodiment, the hydrogen electrode layer 6 is configured to have the fourth region 64, but it may not have the fourth region 64.

[0084] [Modification Example 3] In the above embodiment, the electrolytic cell 1 has been described as an example of the electrochemical cell, but the electrochemical cell is not limited to the electrolytic cell. An electrochemical cell is a general term for an element in which a pair of electrodes are arranged so that an electromotive force is generated from an overall oxidation-reduction reaction in order to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Therefore, the electrochemical cell includes, for example, a fuel cell that uses oxide ions or protons as carriers. [Examples]

[0085] Examples of the electrochemical cell according to the present invention will be described below, but the present invention is not limited to the examples described below.

[0086] (Comparative Example 1) An electrolytic cell according to Comparative Example 1 was produced as follows.

[0087] First, a metal support made of Fe-Cr-Mn alloy steel in which a plurality of communication holes were formed was prepared.

[0088] Next, a slurry for the hydrogen electrode layer was prepared by mixing GDC powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. Then, a molded body of the hydrogen electrode layer was formed by printing the slurry for the hydrogen electrode layer on the first main surface of the metal support by the doctor blade method.

[0089] Next, an electrolyte layer slurry was prepared by mixing YSZ powder, butyral resin, a plasticizer, a dispersant, and a solvent. Then, an electrolyte layer green body was formed by printing the electrolyte slurry so as to cover the green body of the hydrogen electrode layer by the doctor blade method.

[0090] Next, a reaction prevention layer slurry was prepared by mixing GDC powder, polyvinyl alcohol, and a solvent. Then, a reaction prevention layer green body was formed by printing the reaction prevention layer slurry on the electrolyte layer green body by the doctor blade method.

[0091] Next, the green bodies of the hydrogen electrode layer, electrolyte layer, and reaction prevention layer, which were sequentially arranged on the metal support, were fired in the air (1050 °C, 1 hour) to form the hydrogen electrode layer, electrolyte layer, and reaction prevention layer.

[0092] Next, an oxygen electrode layer slurry was prepared by mixing (La,Sr)(Co,Fe)O 3 powder, polyvinyl alcohol, and a solvent. Then, an oxygen electrode layer green body was formed by printing the oxygen electrode layer slurry on the reaction prevention layer by the doctor blade method.

[0093] Next, the oxygen electrode was formed by firing the oxygen electrode layer green body in the air (1000 °C, 1 hour).

[0094] Finally, using crystallized glass, a flow path member made of Fe-Cr-Mn alloy steel was connected to the second main surface of the metal support. Thus, the electrolytic cells according to Examples 1 to 9 were completed.

[0095] (Comparative Example 2 and Examples 1 to 9) The electrolytic cells according to Comparative Example 2 and Examples 1 to 9 were fabricated in the same steps as in Comparative Example 1 except that the hydrogen electrode layer had a multilayer structure.

[0096] Specifically, a slurry for the first region was prepared by mixing GDC powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. At this time, by adjusting the addition amount of NiO powder, the Ni content in the first region was changed as shown in Table 1. Then, the slurry for the first region was printed on the first main surface of the metal support by the doctor blade method to form a molded body of the first region in the hydrogen electrode layer.

[0097] Next, a slurry for the third region was prepared by mixing GDC powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. At this time, by adjusting the addition amount of NiO powder, the Ni content in the third region was changed as shown in Table 1. Then, the slurry for the third region was printed on the molded body of the first region by the doctor blade method to form a molded body of the third region in the hydrogen electrode layer.

[0098] Next, a slurry for the second region was prepared by mixing GDC powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. At this time, by adjusting the addition amount of NiO powder, the Ni content in the second region was changed as shown in Table 1. Then, the slurry for the second region was printed on the molded body of the third region by the doctor blade method to form a molded body of the second region in the hydrogen electrode layer.

[0099] (Initial Evaluation of Electrolytic Cell Performance) First, with the electrolytic cells of Examples 1 to 9 and Comparative Examples 1 and 2 heated to 750°C, hydrogen was supplied from the flow path in the flow path member to the hydrogen electrode layer to reduce NiO contained in the hydrogen electrode layer to Ni.

[0100] Next, while supplying a mixed gas of water vapor and hydrogen (mixing ratio 90:10) to the hydrogen electrode layer, the current density per unit area of the hydrogen electrode layer was 0.5 A / cm 2The cell voltage was measured when electrolysis was carried out by passing a current so as to be constant. In Table 1, when the cell voltage was less than 1.300 [V], it was judged as "〇", and when it was 1.300 [V] or more, it was judged as "×".

[0101] Next, one cycle of the redox cycle was carried out in order, which included a step of supplying a mixed gas of water vapor and hydrogen (mixing ratio 90:10) to the hydrogen electrode layer for 10 hours, a step of supplying a mixed gas of water vapor and hydrogen (mixing ratio 98:2) to the hydrogen electrode layer for 10 hours, and a step of supplying a mixed gas of water vapor and hydrogen (mixing ratio 90:10) to the hydrogen electrode layer for 10 hours.

[0102] Then, in the cross-section along the thickness direction of the hydrogen electrode layer and the metal support, SEM (magnification 1000 times) was used to observe 10 fields at intervals of 500 μm in the plane direction from each end of the interface between the two, and the presence or absence of interface peeling (the part where the non-bonded region at the interface continues for 50 μm or more in the plane direction) was confirmed. In Table 1, when peeling was observed in 2 or more fields, it was judged as "×", when peeling was observed in only 1 field, it was judged as "△", and when no peeling was observed, it was judged as "〇".

[0103] (Durability evaluation of electrolytic cell performance) After the initial evaluation, 100 cycles of the above-mentioned redox cycle were carried out on the electrolytic cells of Examples 1 to 9. Then, similar to the initial evaluation, the cell voltage was measured and judged, and the presence or absence of the peeled part was confirmed.

[0104]

Table 1

[0105] As shown in Table 1, in Examples 1 to 9 where the Ni content in the first region of the hydrogen electrode layer was made lower than the Ni content in the third region, interfacial delamination in the initial evaluation could be suppressed as compared with Comparative Example 1. Such a result was obtained because the expansion / contraction of the first region due to the oxidation-reduction cycle could be reduced. Further, in Examples 1 to 9, the electrolytic cell performance in the initial evaluation could be improved as compared with Comparative Example 2. Such a result was obtained because the electron conductivity and catalytic performance in the third region could be improved. Thus, in Examples 1 to 9, it was possible to achieve both delamination suppression and electrode performance maintenance.

[0106] Further, in Examples 6 to 9 where the Ni content in the second region was made lower than the Ni content in the third region, interfacial delamination after the durability evaluation could be suppressed and the electrolytic cell performance could be improved as compared with Examples 1 to 5. Such a result was obtained because the expansion / contraction due to the oxidation-reduction cycle could be reduced not only in the first region but also in the second region.

[0107] Further, in Examples 8 and 9 where the Ni content in the second region was made lower than the Ni content in the first region, interfacial delamination after the durability evaluation could be more suppressed as compared with Examples 6 and 7. Such a result was obtained because by making the reduction shrinkage amount of the second region smaller than the reduction shrinkage amount of the first region, it was possible to suppress the hydrogen electrode layer from warping in a protruding shape toward the metal support side.

Explanation of Signs

[0108] 1 Electrolytic cell 10 Metal support 11 Communication hole 12 First main surface 13 Second main surface 20 Cell main body part 6 Hydrogen electrode layer 61 First region 62 Second region 63 Third region 64 Fourth region 7 Electrolyte layer 8 Reaction prevention layer 9 Oxygen electrode layer 30 Flow path member 30a Flow path

Claims

1. A metal support having a plurality of communication holes formed on a main surface, A cell main body portion formed on the main surface and having a first electrode layer covering the plurality of communication holes, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer, Comprising: The first electrode layer Has a first region within 5 μm in the thickness direction from a first surface in contact with the metal support, A second region within 5 μm in the thickness direction from a second surface in contact with the electrolyte layer, A third region between the first region and the second region, And has Each of the first region, the second region, and the third region contains nickel and an oxygen ion conductive material, The nickel content in the first region is lower than the nickel content in the third region, The nickel content in the second region is lower than the nickel content in the first region, An electrochemical cell.

2. The nickel content in the second region is lower than the nickel content in the third region, The electrochemical cell according to claim 1.

3. The first electrode layer has a fourth region disposed inside at least one of the plurality of communication holes, The fourth region contains nickel and an oxygen ion conductive material, The nickel content in the fourth region is lower than the nickel content in the third region, The electrochemical cell according to claim 1 or 2.

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