Electrochemical Cell

Abstract

An electrochemical cell (1) comprises a cell body (10), a plate-shaped metal support (20), and a coating layer (40). The metal support (20) has a side surface (20R) that is contiguous with a first main surface (20S) for supporting the cell body (10). The coating layer (40) is composed of a ceramic material, and covers at least a part of the side surface (20R) of the metal support (20).

Description

[Technical field]

[0001] The present invention relates to electrochemical cells. [Background technology]

[0002] In electrochemical cells (electrolysis cells, fuel cells, etc.), a structure in which a cell body is supported by a metal support is known. For example, Patent Document 1 discloses an electrochemical cell including a cell body in which a first electrode layer, an electrolyte layer, and a second electrode layer are laminated in this order on a main surface of a metal support. The metal support has a supply hole for supplying a gas to the first electrode layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-155337 Summary of the Invention [Problem to be solved by the invention]

[0004] Although the metal support has excellent mechanical strength, it has poor heat retention, making it difficult to maintain the temperature of the cell body within an appropriate temperature range.

[0005] An object of the present invention is to provide an electrochemical cell capable of improving heat retention. [Means for solving the problem]

[0006] An electrochemical cell according to a first aspect of the present invention comprises a cell body, a plate-shaped metal support, and a coating layer. The cell body has a first electrode layer, a second electrode layer, and an electrolyte layer. The electrolyte layer is disposed between the first electrode layer and the second electrode layer. The metal support has a first main surface that supports the cell body, and a plurality of supply holes. The coating layer is made of a ceramic material and covers at least a portion of a side surface of the metal support.

[0007] An electrochemical cell according to a second aspect of the present invention is related to the first aspect, wherein the covering layer is connected to the electrolyte layer.

[0008] An electrochemical cell according to a third aspect of the present invention is related to the second aspect, wherein the covering layer is formed integrally with the electrolyte layer, and the ceramic material is the same as the constituent material of the electrolyte layer.

[0009] An electrochemical cell according to a fourth aspect of the present invention is related to the second or third aspect, wherein the coating layer is discontinuous in a cross section perpendicular to the side surface of the metal support.

[0010] An electrochemical cell according to a fifth aspect of the present invention is related to the first aspect, wherein the covering layer is separate from the electrolyte layer.

[0011] An electrochemical cell according to a sixth aspect of the present invention is related to any of the first to fifth aspects above, and includes a flow path member joined to a second main surface of the metal support and forming a flow path between the metal support and the flow path member, and at least a portion of a side surface of the flow path member is covered by a coating layer. Effect of the Invention

[0012] According to the present invention, it is possible to provide an electrochemical cell capable of improving heat retention. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an electrolysis cell according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view perpendicular to the side surface of the metal support according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing the configuration of an electrolysis cell according to the first modification. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of an electrolysis cell according to the second modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Electrolysis cell 1) 1 is a cross-sectional view showing the configuration of an electrolysis cell 1 according to an embodiment. The electrolysis cell 1 is an example of the "electrochemical cell" according to the present invention.

[0015] The electrolysis cell 1 comprises a cell body 10, a metal support 20, a flow path member 30, and a coating layer 40.

[0016] [Cell body 10] The cell main body 10 has a hydrogen electrode layer 6 (cathode), an electrolyte layer 7, a reaction prevention layer 8, and an oxygen electrode layer 9 (anode). The hydrogen electrode layer 6, electrolyte layer 7, reaction prevention layer 8, and oxygen electrode layer 9 are laminated in this order from the metal support 20 side. The hydrogen electrode layer 6, electrolyte layer 7, and oxygen electrode layer 9 are essential components, while the reaction prevention layer 8 is optional.

[0017] [Hydrogen electrode layer 6] The hydrogen electrode layer 6 is disposed between the metal support 20 and the electrolyte layer 7. The hydrogen electrode layer 6 is supported by the metal support 20. In detail, the hydrogen electrode layer 6 is disposed on a first main surface 20S of the metal support 20. The hydrogen electrode layer 6 covers an area of ​​the first main surface 20S of the metal support 20 in which a plurality of supply holes 21 are provided. The hydrogen electrode layer 6 may extend into each supply hole 21. The hydrogen electrode layer 6 is an example of a "first electrode layer" according to the present invention.

[0018] A source gas is supplied to the hydrogen electrode layer 6 through each supply hole 21. The source gas contains CO2 and H2O. The source gas is an example of a "gas" according to the present invention. The hydrogen electrode layer 6 converts H2, CO, and O2 from the source gas in accordance with the electrochemical reaction of co-electrolysis shown in the following formula (1). 2- Generate. Hydrogen electrode layer 6: CO2+H2O+4e - →CO+H2+2O 2- (1)

[0019] The hydrogen electrode layer 6 is made of a porous material having electronic conductivity. The hydrogen electrode layer 6 may have oxide ion conductivity. The hydrogen electrode layer 6 may be made of, for example, 8 mol% yttria-stabilized zirconia (8YSZ), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), (La,Sr)(Cr,Mn)O3, (La,Sr)TiO3, Sr2(Fe,Mo)2O6, (La,Sr)VO3, (La,Sr)FeO3, a mixed material of two or more of these, or a composite of one or more of these and NiO.

[0020] The porosity of the hydrogen electrode layer 6 is not particularly limited, but may be, for example, 5% to 70%. The thickness of the hydrogen electrode layer 6 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0021] The method for forming the hydrogen electrode layer 6 is not particularly limited, and may be a firing method, a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method.

[0022] [Electrolyte layer 7] The electrolyte layer 7 is disposed between the hydrogen electrode layer 6 and the oxygen electrode layer 9. The electrolyte layer 7 covers the entire hydrogen electrode layer 6. The outer edge of the electrolyte layer 7 is joined to the first main surface 20S of the metal support 20. This ensures airtightness between the hydrogen electrode layer 6 side and the oxygen electrode layer 9 side, eliminating the need for a separate seal between the metal support 20 and the electrolyte layer 7.

[0023] The electrolyte layer 7 is formed by discharging the O 2-to the oxygen electrode layer 9. The electrolyte layer 7 is made of a dense material having oxide ion conductivity. The electrolyte layer 7 can be made of, for example, 8YSZ, LSGM (lanthanum gallate), GDC (gadolinium-doped ceria), or the like.

[0024] The electrolyte layer 7 is a sintered body made of a dense material that has ionic conductivity but no electronic conductivity. The electrolyte layer 7 can be made of, for example, YSZ (8YSZ), GDC, ScSZ, SDC, LSGM (lanthanum gallate), or the like.

[0025] The porosity of the electrolyte layer 7 is not particularly limited, but may be, for example, 0.1% to 7%. The thickness of the electrolyte layer 7 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0026] The method for forming the electrolyte layer 7 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0027] [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 to the hydrogen electrode layer 6 with the electrolyte layer 7 interposed therebetween.

[0028] The reaction prevention layer 8 prevents the electrolyte layer 7 from reacting with the oxygen electrode layer 9 to form a reaction layer having a high electrical resistance. The reaction prevention layer 8 is made of an oxide ion conductive material. The reaction prevention layer 8 can be made of GDC, SDC, or the like.

[0029] The porosity of the reaction prevention layer 8 is not particularly limited, but may be, for example, 0.1% to 50%. The thickness of the reaction prevention layer 8 is not particularly limited, but may be, for example, 1 μm to 50 μm.

[0030] The method for forming the reaction prevention layer 8 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0031] [Oxygen electrode layer 9] 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 this embodiment, since the electrolytic cell 1 includes the reaction prevention layer 8, the oxygen electrode layer 9 is disposed on the reaction prevention layer 8. If the electrolytic cell 1 does not include the reaction prevention layer 8, the oxygen electrode layer 9 is disposed on the electrolyte layer 7. The oxygen electrode layer 9 is an example of a "second electrode layer" according to the present invention.

[0032] The oxygen electrode layer 9 reacts with O 2 transferred from the hydrogen electrode layer 6 through the electrolyte layer 7 in accordance with the chemical reaction of the following formula (2): 2- produces O2 from Oxygen electrode layer 9:2O 2- →O2+4e - (2)

[0033] The oxygen electrode layer 9 is made of a porous material having oxide ion conductivity and electron conductivity. The oxygen electrode layer 9 can be made of a compound of one or more of (La,Sr)(Co,Fe)O3, (La,Sr)FeO3, La(Ni,Fe)O3, (La,Sr)CoO3, and (Sm,Sr)CoO3 with an oxide ion conductive material (such as GDC).

[0034] The porosity of the oxygen electrode layer 9 is not particularly limited, but may be, for example, 20% to 60%. The thickness of the oxygen electrode layer 9 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0035] The method for forming the oxygen electrode layer 9 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0036] [Metal support 20] The metal support 20 supports the cell main body 10. The metal support 20 is formed in a plate shape. The metal support 20 may be in a flat plate shape or a curved plate shape. The metal support 20 may have any thickness as long as it can maintain the strength of the electrolysis cell 1, and the thickness is not particularly limited, but may be, for example, 0.1 mm or more and 2.0 mm or less.

[0037] The metal support 20 has a plurality of supply holes 21, a first main surface 20S, a second main surface 20T, and a side surface 20R.

[0038] Each supply hole 21 penetrates the metal support 20 from the first main surface 20S to the second main surface 20T. Each supply hole 21 opens to the first main surface 20S and the second main surface 20T. Each supply hole 21 is formed in a region of the first main surface 20S that is joined to the hydrogen electrode layer 6. The supply hole 21 is connected to a flow path 30a formed between the metal support 20 and the flow path member 30.

[0039] Each supply hole 21 can be formed by mechanical processing (e.g., punching), laser processing, chemical processing (e.g., etching), or the like. Alternatively, when the metal support 20 is made of a porous metal, each supply hole 21 may be an air hole in the porous metal. Therefore, each supply hole 21 does not need to be formed perpendicular to the first main surface 20S and the second main surface 20T.

[0040] The cell body 10 is bonded to the first main surface 20S. The flow path member 30 is bonded to the second main surface 20T. The first main surface 20S is provided on the opposite side of the second main surface 20T. The side surface 20R is connected to each of the first main surface 20S and the second main surface 20T. The side surface 20R may be perpendicular to each of the first main surface 20S and the second main surface 20T, or may be inclined with respect to each of the first main surface 20S and the second main surface 20T. The side surface 20R may be flat, or may be partially or entirely curved or bent, or may have an uneven surface.

[0041] The metal support 20 is made of a metal material. For example, the metal support 20 is made of an alloy material containing Cr (chromium). Examples of such metal materials include Fe-Cr alloy steel (stainless steel, etc.) and Ni-Cr alloy steel. The Cr content in the metal support 20 is not particularly limited, but may be 4% by mass or more and 30% by mass or less.

[0042] The metal support 20 may contain Ti (titanium) and / or Zr (zirconium). The Ti content in the metal support 20 is not particularly limited, but may be 0.01 mol% or more and 1.0 mol% or less. The Zr content in the metal support 20 is not particularly limited, but may be 0.01 mol% or more and 0.4 mol% or less. The metal support 20 may contain Ti as TiO2 (titania) or Zr as ZrO2 (zirconia).

[0043] The metal support 20 may have an oxide film on its surface, which is formed by oxidation of the constituent elements of the metal support 20. A typical example of the oxide film is a chromium oxide film. The oxide film covers the surface of the metal support 20 partially or entirely. The oxide film may also cover the inner wall surface of each supply hole 21 partially or entirely.

[0044] [Flow path member 30] The flow path member 30 is joined to the second main surface 20T of the metal support 20. A flow path 30a is formed between the flow path member 30 and the metal support 20. A source gas is supplied to the flow path 30a. The source gas supplied to the flow path 30a is supplied to the hydrogen electrode layer 6 of the cell main body 10 through each supply hole 21 of the metal support 20.

[0045] The flow path member 30 can be made of, for example, an alloy material. The flow path member 30 may be formed of the same material as the metal support 20. In this case, the flow path member 30 may be substantially integral with the metal support 20.

[0046] The flow path member 30 has a side surface 30R. The side surface 30R of the flow path member 30 is connected to the side surface 20R of the metal support 20. The side surface 30R of the flow path member 30 may be inclined with respect to the side surface 20R of the metal support 20.

[0047] The flow path member 30 has a frame 31 and an interconnector 32. The frame 31 is an annular member that surrounds the side of the flow path 30a. The frame 31 is joined to the second main surface 20T of the metal support 20. The interconnector 32 is a plate-like member that electrically connects the electrolysis cell 1 to an external power source or another electrolysis cell in series. The interconnector 32 is joined to the frame 31.

[0048] Thus, in the flow path member 30 according to this embodiment, the frame 31 and the interconnector 32 are separate members, but the frame 31 and the interconnector 32 may be integral with each other.

[0049] [Coating layer 40] The coating layer 40 is made of a ceramic material. The coating layer 40 covers the side surface 20R of the metal support 20. This makes it possible to suppress heat radiation from the metal support 20, thereby improving the heat retention of the electrolysis cell 1. As a result, it becomes easier to maintain the temperatures of the cell main body 10 and the raw material gas within an appropriate temperature range.

[0050] The covering layer 40 preferably covers the entire side surface 20R of the metal support 20, but may cover only a portion of the side surface 20R of the metal support 20.

[0051] As the ceramic material constituting the coating layer 40, in addition to the respective constituent materials of the electrolyte layer 7, the reaction prevention layer 8, and the oxygen electrode layer 9, perovskite-type complex oxides containing La and Sr, spinel-type complex oxides composed of transition metals such as Mn, Co, Ni, Fe, and Cu, glass materials, etc. can be used. The coating layer 40 may be a laminate in which two or more layers of these materials are laminated. The coating layer 40 is made of a material different from the oxide film (e.g., chromium oxide film) formed on the surface of the metal support 20. In other words, oxides of the constituent elements of the metal support 20 are excluded from the ceramic material constituting the coating layer 40.

[0052] The covering layer 40 according to the present embodiment is joined to the outer edge of the electrolyte layer 7. This makes it possible to suppress heat radiation from the metal support 20 through the gap between the covering layer 40 and the electrolyte layer 7, thereby further improving the heat retention of the electrolysis cell 1.

[0053] Furthermore, when the ceramic material constituting the coating layer 40 is the same as the material constituting the electrolyte layer 7, the coating layer 40 can be formed integrally with the electrolyte layer 7. In this case, the coating layer 40 can be formed at the same time as the electrolyte layer 7, simplifying the manufacturing process of the electrolysis cell 1. Note that when the coating layer 40 is formed integrally with the electrolyte layer 7, no interface exists between the electrolyte layer 7 and the coating layer 40.

[0054] 2 is an enlarged view of a cross section perpendicular to the side surface 20R of the metal support 20 according to the embodiment. As shown in FIG. 2, the coating layer 40 has through holes 41. Therefore, the coating layer 40 is discontinuous in cross-sectional view. This makes it possible to prevent the expansion and contraction of the coating layer 40 from being transmitted to the electrolyte layer 7 even if the coating layer 40 is joined to the electrolyte layer 7. This makes it possible to prevent the electrolyte layer 7 from being damaged (e.g., cracked) by being pulled or pushed by the coating layer 40.

[0055] 2, the covering layer 40 has two through holes 41, but the number of through holes 41 is not particularly limited. In addition, the shape of the through holes 41 in the plan view of the covering layer 40 is not particularly limited, but it is preferable that the through holes 41 extend in a slit shape along the extension direction of the side surface 20R (the direction perpendicular to the paper surface of FIG. 2). This allows the expansion and contraction of the covering layer 40 to be efficiently absorbed, and therefore damage to the electrolyte layer 7 can be further suppressed.

[0056] The porosity of the coating layer 40 is not particularly limited, but may be, for example, 0.1% to 70%. The thickness of the coating layer 40 is not particularly limited, but may be, for example, 0.1 μm to 100 μm. The coverage of the coating layer 40 is not particularly limited, but may be, for example, 20% to 100%.

[0057] The method for forming the coating layer 40 is not particularly limited, but the coating layer 40 can be easily formed by applying a slurry containing a ceramic material to the side surface 20R of the metal support 20.

[0058] (Modification of the embodiment) Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention.

[0059] [Variation 1] In the above embodiment, the covering layer 40 is joined to the electrolyte layer 7, but as shown in Fig. 3, the covering layer 40 may be separated from the electrolyte layer 7. In this case, the expansion and contraction of the covering layer 40 can be reliably prevented from being transmitted to the electrolyte layer 7, so that it is possible to improve the heat retention of the electrolysis cell 1 while preventing damage to the electrolyte layer 7.

[0060] [Variation 2] In the above embodiment, the covering layer 40 covers the side surface 20R of the metal support 20, but it is preferable that the covering layer 40 further covers at least a part of the side surface 30R of the flow path member 30, as shown in Fig. 4. This can also suppress heat radiation from the flow path member 30, thereby further improving the heat retention of the electrolysis cell 1.

[0061] [Variation 3] In the above embodiment, the hydrogen electrode layer 6 functions as a cathode and the oxygen electrode layer 9 functions as an anode, but the hydrogen electrode layer 6 may function as an anode and the oxygen electrode layer 9 may function as a cathode. In this case, the constituent materials of the hydrogen electrode layer 6 and the oxygen electrode layer 9 are switched, and a source gas is passed over the outer surface of the hydrogen electrode layer 6.

[0062] [Variation 4] In the above embodiment, the electrolysis cell 1 has been described as an example of an electrochemical cell, but the electrochemical cell is not limited to the electrolysis 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 a carrier. [Explanation of symbols]

[0063] 1 cell 6 Hydrogen electrode layer 7 Electrolyte layer 8. Reaction prevention layer 9 Oxygen Polar Layer 10 Cell body 20 Metal support 21 Supply hole 20S 1st main surface 20T Second main surface 20R Side 30 Flow path member 30a Flow path 30R side 31 Frame 32 Interconnector 40 Covering layer 41 Through hole

Claims

1. A cell body having a first electrode layer, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer; a plate-shaped metal support having a first main surface supporting the cell main body, a side surface connected to the first main surface, a second main surface provided on the opposite side of the first main surface and connected to the side surface, and a plurality of supply holes; a coating layer made of a ceramic material and covering at least a portion of the side surface of the metal support; Equipped with the coating layer is connected to the electrolyte layer; the plurality of supply holes are open to the first main surface and the second main surface of the metal support, and are not open to the side surface of the metal support; In a cross section perpendicular to the extending direction of the side surface of the metal support, the coating layer is discontinuous. Electrochemical cell.

2. A cell body having a first electrode layer, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer; a plate-shaped metal support having a first main surface supporting the cell main body, a side surface connected to the first main surface, a second main surface provided on the opposite side of the first main surface and connected to the side surface, and a plurality of supply holes; a coating layer made of a ceramic material and covering at least a portion of the side surface of the metal support; a flow path member joined to the second main surface of the metal support and forming a flow path between the metal support and the flow path member; Equipped with the coating layer is connected to the electrolyte layer; the plurality of supply holes are open to the first main surface and the second main surface of the metal support, and are not open to the side surface of the metal support; At least a portion of the side surface of the flow path member is covered with the covering layer. Electrochemical cell.

3. The coating layer is formed integrally with the electrolyte layer, The ceramic material is the same as the constituent material of the electrolyte layer.

3. An electrochemical cell according to claim 1 or 2.

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