Electrochemical Cell

Abstract

An electrolytic cell (1) is provided with a metal sheet (10), a cell body part (20), a current collector part (30), an electroconductive channel member (40), and an electrical connection member (50). The metal sheet (10) has a plurality of through holes (13) communicating to a first main surface (11) and a second main surface (12). The cell body part (20) has a hydrogen electrode layer (21) formed on the first main surface (11) of the metal sheet (10). The current collector part (30) has first portions (31) disposed in the through holes (13) and connected to the hydrogen electrode layer (21). The channel member (40) is joined to the second main surface (12) of the metal sheet (10). The electrical connection member (50) electrically connects the current collector part (30) and the channel member (40).

Description

electrochemical cell

[0001] The present invention relates to electrochemical cells.

[0002] Patent Document 1 discloses a metal-supported electrochemical cell (electrolysis cell, fuel cell, etc.) including a metal plate having a plurality of communication holes formed therein, a cell body supported by the metal plate, and a flow path member forming a gas flow path between the cell body and the metal plate. The cell body has a first electrode layer and a second electrode layer formed on the metal plate, and an electrolyte layer disposed between the first and second electrode layers.

[0003] JP 2020-155337 A

[0004] In the electrochemical cell described in Patent Document 1, the only route for current to flow is between the first electrode layer and the metal plate, and therefore current tends to concentrate in the area of ​​the first electrode layer that contacts the metal plate, causing localized deterioration in that area.

[0005] An object of the present invention is to provide an electrochemical cell capable of suppressing localized deterioration of the first electrode layer.

[0006] An electrochemical cell according to a first aspect of the present invention comprises a metal plate, a cell main body, a current collector, a conductive flow path member, and an electrical connection member. The metal plate has a first main surface, a second main surface, and a plurality of communication holes communicating with the first and second main surfaces. The cell main body has a first electrode layer formed on the first main surface of the metal plate, a second electrode layer, and an electrolyte layer disposed between the first and second electrode layers. The current collector is disposed within the plurality of communication holes and has a plurality of first portions connected to the first electrode layer. The flow path member is bonded to the second main surface and forms a gas flow path between the metal plate and the current collector. The electrical connection member is disposed in the gas flow path and electrically connects at least one of the flow path member and the metal plate to the current collector.

[0007] An electrochemical cell according to a second aspect of the present invention is related to the first aspect, wherein the electrical resistance of a first current route that flows between the first electrode layer and the flow path member via the current collector and the electrical connection member is smaller than the electrical resistance of a second current route that flows between the first electrode layer and the flow path member via the metal plate.

[0008] An electrochemical cell according to a third aspect of the present invention is related to the second aspect, wherein the electrical connection member is connected to each of the current collecting portion and the flow path member by metal-metal connection, and the metal plate has a substrate and an oxide film covering a surface of the substrate.

[0009] An electrochemical cell according to a fourth aspect of the present invention is related to any one of the first to third aspects, and the current collecting portion has a second portion formed in a layer on the second main surface of the metal plate and connected to a plurality of first portions.

[0010] According to the present invention, it is possible to provide an electrochemical cell that can suppress local deterioration of the first electrode layer.

[0011] FIG. 1 is a cross-sectional view of an electrolysis cell according to an embodiment. FIG. 2 is a partial enlarged view of FIG. 1. FIG. 3 is a schematic diagram of a current collecting part according to Modification 3. FIG. 4 is a schematic diagram of a current collecting part according to Modification 3. FIG. 5 is a schematic diagram of a current collecting part according to Modification 3. FIG. 6 is a schematic diagram of an electrical connection member according to Modification 4. FIG. 7 is a schematic diagram of an electrical connection member according to Modification 4.

[0012] An electrolytic cell according to an embodiment will be described with reference to the drawings. The electrolytic cell is an example of an electrochemical cell. In this embodiment, a ceramic solid oxide electrolytic cell (SOEC) will be described as an example of the electrolytic cell. In the following description, the solid oxide electrolytic cell will be abbreviated as "electrolytic cell."

[0013] Fig. 1 is a cross-sectional view of an electrolysis cell 1 according to an embodiment. Fig. 2 is an enlarged view of a portion of Fig. 1.

[0014] As shown in FIG. 1 , the cell 1 includes a metal plate 10 , a cell body 20 , a current collecting portion 30 , a flow path member 40 , and an electrical connection member 50 .

[0015] (Metal Plate 10) The metal plate 10 supports the cell main body 20. In this embodiment, the metal plate 10 is formed in a plate shape. The metal plate 10 may be flat or curved. The thickness of the metal plate 10 is not particularly limited as long as it can maintain the strength of the cell 1, and may be, for example, 0.1 mm or more and 2.0 mm or less.

[0016] As shown in FIG. 1 , the metal plate 10 has a first main surface 11, a second main surface 12, and a plurality of communication holes 13. A cell main body 20 is disposed on the first main surface 11 of the metal plate 10. The second main surface 12 of the metal plate 10 is provided on the opposite side of the first main surface 11. A second portion 32 of a current collector 30 (described later) is disposed on the second main surface 12 of the metal plate 10. In addition, a flow path member 40 is joined to the second main surface 12 of the metal plate 10. In this embodiment, the metal plate 10 and the flow path member 40 are joined by a joint 60, as shown in FIG. 2 .

[0017] The plurality of communication holes 13 are formed in a region corresponding to a hydrogen electrode layer 21, which will be described later. Each communication hole 13 communicates with the first main surface 11 and the second main surface 12. A first portion 31 of a current collector 30, which will be described later, is disposed inside each communication hole 13. In this embodiment, the first portion 31 fills the communication hole 13. Each communication hole 13 opens to the first main surface 11 and the second main surface 12, respectively. The opening of each communication hole 13 on the first main surface 11 side is covered by the hydrogen electrode layer 21. The opening of each communication hole 13 on the second main surface 12 side is covered by a second portion 32 of the current collector 30.

[0018] The area of ​​the communication hole 13 in plan view is, for example, 0.00005 mm ２ More than 1 mm ２ When the shape of the communicating hole 13 in a plan view is substantially circular, the diameter of the communicating hole 13 can be, for example, 10 μm or more and 1000 μm or less. The shape of the communicating hole 13 in a plan view may also be rectangular.

[0019] The communication holes 13 can be formed by mechanical processing (e.g., punching), laser processing, chemical processing (e.g., etching), etc. Furthermore, since the communication holes 13 do not need to be formed along the thickness direction of the metal plate 10, the metal plate 10 may be made of a porous metal having a network of pores.

[0020] As shown in FIG. 2 , the metal plate 10 according to this embodiment is composed of a substrate 14 and an oxide film 15 .

[0021] The substrate 14 is made of a metal material. For example, the substrate 14 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 plate 10 is not particularly limited, but can be set to 4% by mass or more and 30% by mass or less.

[0022] The substrate 14 may contain Ti (titanium) or Zr (zirconium). The content of Ti in the substrate 14 is not particularly limited, but may be 0.01 mol % or more and 1.0 mol % or less. The content of Zr in the substrate 14 is not particularly limited, but may be 0.01 mol % or more and 0.4 mol % or less. The substrate 14 may contain Ti in the form of TiO ２ (titania), or Zr may be contained as ZrO ２ It may be contained as (zirconia).

[0023] The oxide film 15 covers at least a portion of the surface of the substrate 14. In this embodiment, as shown in Fig. 2, the oxide film 15 covers the surface of the substrate 14 except for the region where the bonding portion 60 is bonded. Therefore, the oxide film 15 is interposed between the substrate 14 and a hydrogen electrode layer 21 (described later) and between the substrate 14 and the current collector 30.

[0024] The oxide coating 15 can be made of an oxide of a constituent element of the base material 14. For example, when the base material 14 is made of an alloy material containing Cr, the oxide coating 15 may contain chromium oxide as a main component. "Containing chromium oxide as a main component" means that chromium oxide accounts for 70 wt % or more of the oxide coating 15.

[0025] The thickness of the oxide film 15 is not particularly limited, but may be, for example, 0.1 μm or more and 20 μm or less.

[0026] The oxide film 15 can be formed by applying a material paste to the surface of the substrate 14, but can also be formed by leaving the substrate 14 in the air to oxidize it.

[0027] 1, the cell body 20 is disposed on the first main surface 11 of the metal plate 10. The cell body 20 has a hydrogen electrode layer 21 (cathode), an electrolyte layer 22, a reaction prevention layer 23, and an oxygen electrode layer 24 (anode). The hydrogen electrode layer 21 is an example of a "first electrode layer" according to the present invention, and the oxygen electrode layer 24 is an example of a "second electrode layer" according to the present invention.

[0028] The hydrogen electrode layer 21, the electrolyte layer 22, the reaction prevention layer 23, and the oxygen electrode layer 24 are stacked in this order from the metal plate 10 side. However, the cell body 20 does not necessarily have to have the reaction prevention layer 23.

[0029] 1, the hydrogen electrode layer 21 is formed on the first main surface 11 of the metal plate 10. The hydrogen electrode layer 21 is provided so as to cover the region of the first main surface 11 in which the plurality of communication holes 13 are provided.

[0030] The source gas is supplied to the hydrogen electrode layer 21 through each of the communication holes 13 of the metal plate 10. In this embodiment, the source gas contains at least H ２ Contains O.

[0031] The raw material gas is H ２ When only O is contained, the hydrogen electrode layer 21 converts the raw material gas into H according to the electrochemical reaction of water electrolysis shown in the following formula (1): ２ Generate.

[0032] Hydrogen electrode layer 21: H2O+2e-→H2+O2- (1)

[0033] The raw material gas is H ２ O plus CO ２ In this case, the hydrogen electrode layer 21 converts H from the source gas according to the co-electrolytic electrochemical reactions shown in the following formulas (2), (3), and (4). ２ , CO and O ２－ Generate.

[0034] Hydrogen electrode layer 21: CO ２ +H ２ O+4e － →CO+H ２ +20 ２－ ... (2) H ２ Electrochemical reaction of O: H ２ O + 2e－ →H ２ +O ２－ ... (3) CO ２ Electrochemical reaction of: CO ２ +2e － →CO+O ２－ ...(4)

[0035] The hydrogen electrode layer 21 is made of a conductive porous material. The hydrogen electrode layer 21 may have oxide ion conductivity. For example, the hydrogen electrode layer 21 may be made of 8 mol % yttria-stabilized zirconia (8YSZ), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), or (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 , a mixed material of two or more of these, or a composite material of one or more of these with NiO.

[0036] The porosity of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 5% to 70%. The thickness of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0037] The method for forming the hydrogen electrode layer 21 is not particularly limited, and may be 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, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method.

[0038] 1 , the electrolyte layer 22 is disposed between the hydrogen electrode layer 21 and the oxygen electrode layer 24. In this embodiment, since the cell main body 20 has the reaction prevention layer 23, the electrolyte layer 22 is interposed between the hydrogen electrode layer 21 and the reaction prevention layer 23.

[0039] The electrolyte layer 22 is disposed so as to cover the entire hydrogen electrode layer 21. The outer periphery of the electrolyte layer 22 is bonded to the first main surface 11 of the metal plate 10. This ensures airtightness between the hydrogen electrode layer 21 and the oxygen electrode layer 24, eliminating the need for a separate seal between the metal plate 10 and the electrolyte layer 22.

[0040] The electrolyte layer 22 absorbs the O generated in the hydrogen electrode layer 21. ２－ The electrolyte layer 22 is a dense body having oxide ion conductivity. Examples of oxide ion conductive materials include YSZ (yttria-stabilized zirconia, e.g., 8YSZ), GDC (gadolinium-doped ceria), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), LSGM (lanthanum gallate), and composite materials thereof.

[0041] The porosity of the electrolyte layer 22 is not particularly limited, but may be, for example, 0.1% to 7%. The thickness of the electrolyte layer 22 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0042] The method for forming the electrolyte layer 22 is not particularly limited, and for example, a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0043] 1, the reaction prevention layer 23 is disposed on the electrolyte layer 22. The reaction prevention layer 23 is interposed between the electrolyte layer 22 and the oxygen electrode layer 24. The reaction prevention layer 23 prevents the constituent material of the oxygen electrode layer 24 from reacting with the constituent material of the electrolyte layer 22 to form a reaction layer with high electrical resistance.

[0044] The reaction prevention layer 23 is made of a material having oxide ion conductivity, and can be made of a ceria-based material such as GDC or SDC.

[0045] The porosity of the reaction prevention layer 23 is not particularly limited, but may be, for example, 0% to 50%. The thickness of the reaction prevention layer 23 is not particularly limited, but may be, for example, 3 μm to 50 μm.

[0046] The method for forming the reaction prevention layer 23 is not particularly limited, and for example, a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0047] 1 , the oxygen electrode layer 24 is disposed on the opposite side of the electrolyte layer 22 from the hydrogen electrode layer 21. In this embodiment, the reaction prevention layer 23 is disposed between the electrolyte layer 22 and the oxygen electrode layer 24, and therefore the oxygen electrode layer 24 is connected to the reaction prevention layer 23. If the reaction prevention layer 23 is not disposed between the electrolyte layer 22 and the oxygen electrode layer 24, the oxygen electrode layer 24 is connected to the electrolyte layer 22.

[0048] The oxygen electrode layer 24 reacts with O 2 transferred from the hydrogen electrode layer 21 via the electrolyte layer 22 in accordance with the chemical reaction of the following formula (5): ２－ From O ２ Generate.

[0049] Oxygen electrode layer 24: 2O ２－ →O ２ +4e － ...(5)

[0050] The oxygen electrode layer 24 is made of a porous material having oxide ion conductivity and electrical conductivity, such as (La, Sr)(Co, Fe)O. ３ , (La,Sr)FeO ３ , La(Ni,Fe)O ３ , (La,Sr)CoO ３ , and (Sm,Sr)CoO ３ The insulating layer 10 may be made of a composite material of one or more of the above and an oxide ion conductive material (such as GDC).

[0051] The porosity of the oxygen electrode layer 24 is not particularly limited, but may be, for example, 20% to 60%. The thickness of the oxygen electrode layer 24 is not particularly limited, but may be, for example, 1 μm to 100 μm.

[0052] The method for forming the oxygen electrode layer 24 is not particularly limited, and may be a firing method, a spray coating method, a PVD method, a CVD method, or the like.

[0053] 1, the current collecting part 30 is disposed on the opposite side of the hydrogen electrode layer 21 from the electrolyte layer 22. The current collecting part 30 is connected to the hydrogen electrode layer 21.

[0054] The current collecting section 30 can be made of a conductive metal material, a conductive ceramic material, a composite material of a conductive metal material and a conductive ceramic material, or a composite material of a non-conductive ceramic material and a conductive metal material. Examples of conductive metal materials include Fe, Ni, Cu, Au, and Pt. Examples of conductive ceramic materials include (La,Sr)MnO. ３ , La(Cr,Ca)O ３ , (La,Sr)TiO ３ Examples of ceramic materials that do not have electrical conductivity include ZrO ２ , CeO ２ , Y ２ O ３ , Al ２ O ３ , Mg ２ SiO ｘ Examples include:

[0055] The current collecting portion 30 may be made of the same material as the hydrogen electrode layer 21. In this case, the current collecting portion 30 may be substantially integral with the hydrogen electrode layer 21.

[0056] The porosity of the current collecting portion 30 is not particularly limited, but can be, for example, 30% or more and 70% or less.

[0057] As shown in FIG. 1 , the current collecting portion 30 has a plurality of first portions 31 and second portions 32 .

[0058] Each first portion 31 is disposed in a corresponding communication hole 13 of the metal plate 10. However, each first portion 31 may contain voids, cracks, etc. inside. Each first portion 31 is connected to the hydrogen electrode layer 21.

[0059] The diameter of the first portion 31 is substantially the same as the diameter of the communicating hole 13. In the thickness direction of the metal plate 10, the height of the first portion 31 is substantially the same as the length of the communicating hole 13.

[0060] The second portion 32 is formed in a layer on the second main surface 12 of the metal plate 10. The second portion 32 is provided so as to cover an area of ​​the second main surface 12 in which the plurality of communication holes 13 are provided. The second portion 32 is connected to each of the first portions 31. The second portion 32 is formed integrally with each of the first portions 31.

[0061] The thickness of the second portion 32 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0062] The first portion 31 can be formed by injecting a material paste containing the constituent material of the current collecting portion 30 into each of the communicating holes 13 of the metal plate 10, followed by firing. The second portion 32 can be formed by applying the material paste to the second main surface 12 of the metal plate 10, followed by firing. The first portion 31 and the second portion 32 may be formed by firing simultaneously. Note that the method for forming the first portion 31 and the second portion 32 is not limited to firing, and for example, vapor phase growth methods such as thermal spraying, aerosol deposition (AD), and sputtering can be used.

[0063] [Flow Channel Member 40] The flow channel member 40 is joined to the second main surface 12 of the metal plate 10. The flow channel member 40 is formed in a tray shape that opens toward the metal plate 10. The opening of the flow channel member 40 is covered by the metal plate 10. This forms a gas flow channel 41 between the flow channel member 40 and the metal plate 10. In this embodiment, a raw material gas is supplied to the gas flow channel 41.

[0064] As shown in FIG. 1 , the flow path member 40 includes a frame 42 and an interconnector 43 .

[0065] The frame 42 is joined to the second main surface 12 of the metal plate 10 via a joint 60. The joint 60 is formed by welding or brazing the base material 14 of the metal plate 10 to the base material 44 of the frame 42. The frame 42 is an annular member that surrounds the gas flow path 41. The frame 42 is arranged to surround the periphery of the current collecting part 30.

[0066] As shown in Fig. 2, the frame 42 according to this embodiment is composed of a base material 44 and an oxide film 45. The base material 44 is made of a metal material. The configuration of the base material 44 is similar to that of the base material 14 of the metal plate 10 described above. The oxide film 45 covers at least a portion of the surface of the base material 44. In this embodiment, as shown in Fig. 2, the oxide film 45 covers the surface of the base material 44 except for the areas where the joints 60 and the joints 70 described below are joined. The configuration of the oxide film 45 is similar to that of the oxide film 15 of the metal plate 10 described above.

[0067] The interconnector 43 is a plate-like member for electrically connecting the electrolytic cell 1 to an external power source or another electrolytic cell in series. The interconnector 43 is joined to the frame 42 via a joint 70. The joint 70 is formed by welding or brazing a base material 44 of the frame 42 to a base material 46 of the interconnector 43. The interconnector 43 faces the current collecting part 30 across the gas flow path 41.

[0068] As shown in FIG. 2 , the interconnector 43 according to this embodiment is composed of a substrate 46 and an oxide film 47. The substrate 46 is composed of a metal material. The configuration of the substrate 46 is similar to that of the substrate 14 of the metal plate 10 described above. The oxide film 47 covers at least a portion of the surface of the substrate 46. In this embodiment, as shown in FIG. 2 , the oxide film 47 covers the surface of the substrate 46 excluding the region where the joint portion 70 is joined and the connection region 46 a to which the electrical connection member 50 is connected. The configuration of the oxide film 47 is similar to that of the oxide film 15 of the metal plate 10 described above.

[0069] In this embodiment, the frame body 42 and the interconnector 43 are separate members, but the frame body 42 and the interconnector 43 may be an integrated member.

[0070] (Electrical connection member 50) As shown in Fig. 1 , the electrical connection member 50 is disposed in the gas flow path 41. The electrical connection member 50 electrically connects the current collecting unit 30 and the flow path member 40. More specifically, as shown in Fig. 2 , the electrical connection member 50 electrically connects the second portion 32 of the current collecting unit 30 and the substrate 46 of the interconnector 43 of the flow path member 40.

[0071] The electrical connection member 50 preferably has air permeability so as not to impede the flow of the source gas flowing through the gas flow path 41. The air permeability of the electrical connection member 50 can be obtained, for example, by making the electrical connection member 50 itself a porous body, or by making the electrical connection member 50 out of a mesh material woven in a net shape.

[0072] The electrical connection member 50 is made of a metal material that is conductive and does not form an oxide film on its surface, such as Ni, Fe, Cu, Au, or Pt.

[0073] In this embodiment, the electrical connection member 50 is connected to the second portion 32 of the current collecting unit 30 by a metal-metal connection. A metal-metal connection means that the two components are electrically connected only via metal elements. The metal-metal connection between the current collecting unit 30 and the electrical connection member 50 includes a direct electrical connection formed by direct contact between the metal elements contained in the second portion 32 and the metal elements contained in the electrical connection member 50, and an indirect electrical connection formed between the metal elements contained in the second portion 32 and the metal elements contained in the electrical connection member 50 via metal elements contained in a conductive bonding material. A direct electrical connection can be formed by directly contacting the electrical connection member 50 with the second portion 32. An indirect electrical connection can be formed by joining the electrical connection member 50 to the second portion 32 using a conductive bonding material. A metal paste containing a metal element can be used as the conductive bonding material.

[0074] In this embodiment, the electrical connection member 50 is connected to the interconnector 43 of the flow path member 40 by metal-metal connection. The metal-metal connection between the flow path member 40 and the electrical connection member 50 includes a direct electrical connection formed by direct contact between the metal elements contained in the base material 46 and the metal elements contained in the electrical connection member 50, and an indirect electrical connection formed between the metal elements contained in the base material 46 and the metal elements contained in the electrical connection member 50 via metal elements contained in a conductive bonding material. A direct electrical connection can be formed by directly contacting the electrical connection member 50 with the base material 46, or by welding them together. An indirect electrical connection can be formed by joining the electrical connection member 50 to the base material 46 using a conductive bonding material, or by brazing. As the conductive bonding material, a metal paste or brazing material containing a metal element can be used.

[0075] (Current Routes) In the electrolysis cell 1 according to this embodiment, as shown in FIG. 2 , there are two routes for the current flowing between the hydrogen electrode layer 21 and the flow path member 40: a first current route R1 and a second current route R2.

[0076] The first current route R1 is a route from the hydrogen electrode layer 21 to the flow path member 40 via the current collector 30 and the electrical connection member 50. Specifically, the first current route R1 is a route through which current flows in the order of the hydrogen electrode layer 21 → the current collector 30 → the electrical connection member 50 → the interconnector 43. The first current route R1 is a route through which current does not flow directly from the hydrogen electrode layer 21 to the metal plate 10, and is a route that does not exist in conventional metal-supported electrolysis cells (see, for example, JP 2020-155337 A).

[0077] The second current route R2 is a route from the hydrogen electrode layer 21 to the flow path member 40 without passing through the current collector 30 and the electrical connection member 50. Specifically, the second current route R2 is a route through which current flows in the following order: hydrogen electrode layer 21 → metal plate 10 → joint 60 → frame 42 → joint 70 → interconnector 43. The second current route R2 is a route through which current flows directly from the hydrogen electrode layer 21 to the metal plate 10, and is a route that exists in conventional metal-supported electrolysis cells.

[0078] In this way, the existence of the first current route R1 through which current flows from the hydrogen electrode layer 21 to the current collecting part 30 and the second current route R2 through which current flows from the hydrogen electrode layer 21 to the metal plate 10 allows current to flow using the entire hydrogen electrode layer 21. This prevents current from concentrating on the second current route R2, thereby preventing local deterioration of the region of the hydrogen electrode layer 21 that contacts the metal plate 10.

[0079] Furthermore, because the oxide film 15 is interposed between the substrate 14 of the metal plate 10 and the hydrogen electrode layer 21, the oxide film 15 would heat up due to the current flowing through the second current route R2. However, as described above, current concentration on the second current route R2 can be suppressed, thereby suppressing heat generation in the oxide film 15. This suppresses interdiffusion of elements between the hydrogen electrode layer 21 and the metal plate 10, thereby further suppressing local deterioration of the region of the hydrogen electrode layer 21 that contacts the metal plate 10. Note that the current flowing through the first current route R1 does not pass through the oxide film 15, and therefore does not cause problems due to heat generation in the oxide film 15.

[0080] As described above, the electrical connection member 50 is connected metal-to-metal with both the current collecting section 30 and the flow path member 40, thereby minimizing the electrical resistance of the first current route R1. Meanwhile, the oxide film 15 is interposed between the base material 14 of the metal plate 10 and the hydrogen electrode layer 21, increasing the electrical resistance of the second current route R2. Therefore, the electrical resistance of the first current route R1 is smaller than the electrical resistance of the second current route R2. Therefore, the current flows from the hydrogen electrode layer 21 to the flow path member 40 via the first current route R1 as the main route and the second current route R2 as the sub-route. This further reduces heat generation in the oxide film 15, thereby further preventing interdiffusion of elements between the hydrogen electrode layer 21 and the metal plate 10. As a result, localized deterioration of the region of the hydrogen electrode layer 21 that contacts the metal plate 10 can be further suppressed.

[0081] (Modifications) 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.

[0082] [Variation 1] In the above embodiment, the hydrogen electrode layer 21 functions as a cathode and the oxygen electrode layer 24 functions as an anode. However, the hydrogen electrode layer 21 may function as an anode and the oxygen electrode layer 24 may function as a cathode. Specifically, the positions of the hydrogen electrode layer 21, the reaction prevention layer 23, and the oxygen electrode layer 24 are interchanged, and a source gas is passed over the outer surface of the hydrogen electrode layer 21. In this case, the oxygen electrode layer 21 serves as the first electrode layer according to the present invention, and the hydrogen electrode layer 21 serves as the second electrode layer according to the present invention.

[0083] [Variation 2] 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 an 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 to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Therefore, the electrochemical cell may be a solid oxide fuel cell (SOFC) that uses oxide ions or protons as carriers. In this case, the fuel electrode (anode) corresponds to the first electrode layer according to the present invention, and the air electrode (cathode) corresponds to the second electrode layer according to the present invention.

[0084] [Modification 3] In the above embodiment, the current collecting section 30 has a plurality of first portions 31 and a layer-like second portion 32. However, as shown in Fig. 3, the current collecting section 30 does not have to have the second portion 32. In this case, the electrical connection member 50 is connected to the first portion 31 of the current collecting section 30 by metal-metal connection.

[0085] Furthermore, when the current collecting portion 30 does not have the second portion 32, the first portion 31 may protrude into the gas flow path 41 from the opening of the communication hole 13 on the second main surface 12 side, as shown in FIG. 4 .

[0086] Furthermore, when the current collecting part 30 does not have the second portion 32, the first portion 31 does not have to fill the entire communicating hole 13. For example, as shown in Fig. 5, the first portion 31 does not have to reach the opening of the communicating hole 13 on the second main surface 12 side. Alternatively, as shown in Fig. 6, the first portion 31 may be arranged in a layer on at least a part of the inner circumferential surface of the communicating hole 13.

[0087] [Modification 4] In the above embodiment, the electrical connection member 50 is connected to the interconnector 43 of the flow path member 40, but this is not limitative.

[0088] 7 , the electrical connection member 50 may be connected to the frame 42 of the flow path member 40. In this case, the first current route R1 is a route through which current flows in the order of the hydrogen electrode layer 21 → current collecting portion 30 → electrical connection member 50 → frame 42 → joint 70 → interconnector 43. The electrical connection member 50 is preferably connected to the frame 42 of the flow path member 40 by metal-to-metal connection. Note that the electrical connection member 50 may be connected to both the frame 42 and the interconnector 43 of the flow path member 40.

[0089] 8, the electrical connection member 50 may be connected to the metal plate 10. In this case, the first current route R1 is a route through which current flows in the following order: hydrogen electrode layer 21 → current collecting portion 30 → electrical connection member 50 → metal plate 10 → joint 60 → frame 42 → joint 70 → interconnector 43. The electrical connection member 50 is preferably connected to the metal plate 10 by metal-to-metal connection. The electrical connection member 50 may be connected to both the flow path member 40 and the metal plate 10. It is sufficient that the electrical connection member 50 is connected to at least one of the flow path member 40 and the metal plate 10.

[0090] REFERENCE SIGNS LIST 1 Electrolysis cell 10 Metal plate 11 First main surface 12 Second main surface 13 Communication hole 14 Substrate 15 Oxide film 20 Cell body 21 Hydrogen electrode layer 22 Electrolyte layer 23 Reaction prevention layer 24 Oxygen electrode layer 30 Current collector 31 First portion 32 Second portion 40 Flow path member 41 Gas flow path 42 Frame 43 Interconnector 50 Electrical connection member

Claims

1. An electrochemical cell comprising: a metal plate having a first main surface, a second main surface, and a plurality of through holes communicating with the first main surface and the second main surface; a cell body having a first electrode layer formed on the first main surface of the metal plate, a second electrode layer, and an electrolyte layer disposed between the first electrode layer and the second electrode layer; a current collector disposed in the plurality of through holes and having a plurality of first portions connected to the first electrode layer; a conductive flow path member bonded to the second main surface of the metal plate and forming a gas flow path between the metal plate and the conductive flow path member; and an electrical connection member disposed in the gas flow path and electrically connecting the current collector to at least one of the flow path member and the metal plate.

2. The electrochemical cell according to claim 1, wherein the electrical resistance of a first current route that flows between the first electrode layer and the flow path member via the current collecting portion and the electrical connection member is smaller than the electrical resistance of a second current route that flows between the first electrode layer and the flow path member via the metal plate.

3. The electrochemical cell according to claim 2, wherein the electrical connection member is connected to each of the current collecting portion and the flow path member by metal-metal connection, and the metal plate has a base material and an oxide film covering the surface of the base material.

4. The electrochemical cell according to claim 1, wherein the current collecting portion is formed in a layer on the second main surface of the metal plate and has a second portion connected to the plurality of first portions.

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