JP2005302424A - Electrolyte membrane for fuel cell, fuel cell, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte membrane that prevents a short circuit in an electrolyte membrane even if cracks are generated in the electrolyte membrane when manufacturing and operating a fuel cell. <P>SOLUTION: First, a metal layer 22 with hydrogen permeability is prepared as a base material having an electrical conductivity when manufacturing the fuel cell, and subsequently an electrolyte membrane 21 formed by an electrolyte is formed on the metal layer 22 with hydrogen permeability. The electrolyte membrane 21 includes a first electrolyte layer 25 and a second electrolyte layer 26. The first electrolyte layer 25 is formed by causing an electrolyte crystal to grow in a fixed direction in relation to the surface of the base material. The second electrolyte layer 26 is formed by causing the electrolyte crystal to grow on the first electrolyte layer 25 in a different direction form the growing direction of the crystal in the first electrolyte layer 25. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrolyte membrane for a fuel cell, a fuel cell, and a method for producing them.

  As one type of fuel cell, a fuel cell using a solid oxide that is a ceramic as an electrolyte is known. Ceramics used as an electrolyte generally have the property of being more brittle than metals and polymers. Therefore, in a fuel cell formed by laminating a member containing a solid oxide, when each member is heated and thermally expanded at the time of manufacture and operation, mainly due to the difference in expansion coefficient from the adjacent member, Cracks may occur in the solid oxide. The problem of crack generation is a problem that can occur not only when the electrolyte membrane is formed of ceramics but also when a member (for example, an electrode) other than the electrolyte membrane is further formed of ceramics. Patent Document 1 discloses a configuration in which a gas permeable metal member is used instead of a conventional ceramic member as an electrode member laminated with a solid oxide that is an electrolyte membrane. In this way, the electrode member is formed of metal instead of ceramics, thereby preventing problems such as cracks in the electrode member and improving the reliability of the entire fuel cell.

JP-A-4-345762 JP-A-5-62700 JP-A 64-50496

  However, even if the electrode is formed of a metal material as described above, the problem of crack generation in the electrolyte membrane made of a solid oxide remains. If a crack occurs in the electrolyte membrane during the manufacture of the fuel cell, there is a possibility that an electrode material enters the crack generated in the electrolyte membrane and a short circuit occurs in the electrolyte membrane. Further, if a crack occurs in the electrolyte membrane during operation of the fuel cell, the electrode material softened with the temperature rise during operation may enter the crack and cause a short circuit in the electrolyte membrane.

  The present invention has been made to solve the above-described conventional problems. Even when a crack occurs in the electrolyte membrane during manufacturing or operation of the fuel cell, a short circuit in the electrolyte membrane is prevented to prevent the shortage of the fuel cell. The purpose is to increase reliability.

To achieve the above object, the present invention provides a method for producing an electrolyte membrane for a fuel cell,
(A) forming a first layer of the first electrolyte by growing a crystal of the first electrolyte in a certain direction;
(B) a second layer made of the second electrolyte by growing a crystal of the second electrolyte on the first layer in a specific direction different from the growth direction of the crystal in the first layer. And the step of forming the gist.

  According to the method for producing an electrolyte membrane for a fuel cell of the present invention configured as described above, in each of the first layer and the second layer, the direction of the grain boundary formed over the thickness direction of the layer is: In accordance with the crystal growth direction, there are obtained electrolyte membranes that are aligned in a certain direction within the layer, and that the crystal grain boundaries formed in the thickness direction of the layers are different from each other between the first layer and the second layer. It is done. Therefore, even if a crack occurs in the electrolyte membrane, occurrence of a short circuit through the electrolyte membrane can be suppressed.

In the method for producing an electrolyte membrane for a fuel cell of the present invention,
(C) Growing a predetermined electrolyte crystal on a plurality of previously formed layers made of the electrolyte crystal in a direction different from the crystal growth direction in the uppermost layer of the plurality of already formed layers. Forming another layer of the predetermined electrolyte,
The step (c) may be performed once or more.

  In such a case, when a crack occurs in an electrolyte membrane composed of three or more layers, the crack direction changes between adjacent layers, so that the effect of suppressing the occurrence of a short circuit through the electrolyte membrane can be enhanced. it can.

In the method for producing an electrolyte membrane for a fuel cell of the present invention,
The step of forming each of the layers includes the step of forming the material from a direction corresponding to a direction in which the crystal is grown with respect to a predetermined base material while providing energy capable of crystallizing the material forming the electrolyte layer. It may be released.

  With such a configuration, electrolyte crystals can be grown on a predetermined base material in a direction corresponding to the direction in which the material forming each electrolyte layer is released. At that time, by providing sufficient energy for crystallization, each layer can be constituted by columnar crystals whose longitudinal direction is the crystal growth direction. The step of releasing and crystallizing the material forming each electrolyte layer in a specific direction can be easily performed by, for example, PVD.

The method for producing the fuel cell of the present invention comprises:
(A) preparing a conductive base material for constituting the fuel cell;
(B) forming an electrolyte membrane on the substrate;
The step (b)
(B-1) forming a first layer of the first electrolyte by growing a crystal of the first electrolyte in a certain direction on the substrate;
(B-2) A second electrolyte made of the second electrolyte is grown on the first layer by growing a second electrolyte crystal in a specific direction different from the crystal growth direction in the first layer. And a step of forming the layer.

  According to the method of manufacturing a fuel cell of the present invention configured as described above, in each of the first layer and the second layer, the direction of the crystal grain boundary formed over the thickness direction of the layer is crystal growth. A fuel cell comprising electrolyte membranes that are substantially the same in a layer according to the direction and that have different grain boundary directions formed across the thickness direction of the layer between the first layer and the second layer. Can be manufactured. Therefore, even if a crack occurs in the electrolyte membrane, the occurrence of a short circuit via the electrolyte membrane can be suppressed.

In the method for producing a fuel cell of the present invention,
The step (b) further includes
(B-3) Growing a predetermined electrolyte crystal in a direction different from the crystal growth direction in the uppermost layer of the plurality of already formed layers on the plurality of already formed layers made of the electrolyte crystals. A step of forming another layer of the predetermined electrolyte,
The step (b-3) may be performed once or more.

  With such a configuration, the number of layers constituting the electrolyte membrane can be increased according to the number of times of performing the step (b-3), and crystal grains formed across the thickness direction of each layer between adjacent layers. Electrolyte membranes having different field directions can be used. Therefore, it is possible to effectively prevent the conductive material constituting the member provided adjacent to the electrolyte membrane from entering the crack and to prevent a short circuit through the electrolyte membrane.

In the method for producing a fuel cell of the present invention,
The step of forming each layer in the step (b) includes the step of forming the electrolyte layer from a direction corresponding to a direction in which the crystal is grown with respect to the base material while giving energy capable of crystallization. The material may be released.

  With this configuration, electrolyte crystals can be grown in a direction corresponding to the direction in which the material forming each electrolyte layer is released. At that time, by providing sufficient energy for crystallization, each layer can be constituted by columnar crystals whose longitudinal direction is the crystal growth direction. The step of releasing and crystallizing the material forming each layer in a specific direction can be easily performed by, for example, PVD.

The fuel cell manufacturing method of the present invention further includes:
(C) It is good also as providing the process of forming an electrode on the said electrolyte membrane using an electroconductive material.

  In such a case, even if a crack has occurred in the electrolyte membrane, when the electrode is formed using a conductive material on the electrolyte membrane, the penetration of the conductive material into the crack is prevented by the crack shape. Further, it is possible to prevent a short circuit through the electrolyte membrane between the conductive substrate and the electrode.

  In the fuel cell manufacturing method of the present invention, the base material may be a hydrogen permeable metal film.

  If an electrolyte membrane is formed using a hydrogen permeable metal membrane as a base material, even if a crack occurs in the electrolyte membrane, cross leak between the fuel gas and the oxidizing gas through the electrolyte membrane is caused by the hydrogen permeable metal membrane. The effect that it can be prevented is further obtained.

  In the method for producing an electrolyte membrane for a fuel cell or the method for producing a fuel cell of the present invention, the step of forming each layer constituting the electrolyte membrane may be performed by growing crystals of the same kind of electrolyte. Thereby, in the electrolyte membrane in which the type of the electrolyte to be configured is uniform, the occurrence of a short circuit through the electrolyte membrane can be suppressed. Further, in the method for producing an electrolyte membrane for a fuel cell or the method for producing a fuel cell of the present invention, the step of forming each layer constituting the electrolyte membrane may be performed by growing solid oxide crystals. Thereby, in the electrolyte membrane formed of the solid oxide, it is possible to suppress the occurrence of a short circuit through the electrolyte membrane.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in the form of an electrolyte membrane for a fuel cell or a fuel cell.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Fuel cell configuration:
B. Production method:
C. Variation:

A. Fuel cell configuration:
FIG. 1 is a schematic cross-sectional view showing an outline of the configuration of a single cell 20 constituting a fuel cell according to a preferred embodiment of the present invention. The single cell 20 includes a hydrogen permeable metal layer 22, an electrolyte membrane 21, a cathode electrode 24, and gas separators 27 and 29. Between the gas separator 27 and the hydrogen permeable metal layer 22, an in-cell fuel gas channel 30 through which a fuel gas containing hydrogen passes is formed. Further, between the gas separator 29 and the cathode electrode 24, an in-single cell oxidizing gas passage 32 through which an oxidizing gas containing oxygen passes is formed. Hereinafter, a structure including the hydrogen permeable metal layer 22, the electrolyte membrane 21, and the cathode electrode 24 is referred to as an MEA (Membrane Electrode Assembly) 40. Although the single cell 20 is shown in FIG. 1, the actual fuel cell of this embodiment has a stack structure in which a plurality of the single cells 20 of FIG. 1 are stacked. Although illustration is omitted, in order to adjust the internal temperature of the stack structure, a refrigerant flow path through which the refrigerant passes may be provided between the single cells or every time a predetermined number of single cells are stacked. good.

  The hydrogen permeable metal layer 22 is a layer formed of a metal having hydrogen permeability. Such a hydrogen permeable metal layer 22 can be formed of, for example, palladium (Pd) or a Pd alloy. Alternatively, a group 5 metal such as vanadium (V) (in addition to V, niobium, tantalum, etc.) or a group 5 metal alloy is used as a base material, and Pd is formed on at least one surface thereof (on the side of the fuel cell in the single cell) Or a multilayer film in which a Pd alloy layer is formed. In the hydrogen permeable metal layer 22, at least Pd (or Pd alloy) constituting the surface on the side of the fuel gas flow path 30 in the single cell dissociates hydrogen molecules when hydrogen permeates the hydrogen permeable metal layer 22. Has activity. In the present embodiment, the hydrogen permeable metal layer 22 functions as an anode electrode.

The electrolyte membrane 21 is a layer made of a solid electrolyte having proton conductivity. As the solid electrolyte constituting the electrolyte membrane 21, for example, BaCeO ₃ or SrCeO ₃ based ceramic proton conductors can be used. Since the electrolyte membrane 21 is formed on the dense hydrogen permeable metal layer 22, it can be sufficiently thinned. Therefore, the membrane resistance of the solid oxide can be reduced, and the fuel cell can be operated at about 200 to 600 ° C., which is lower than the operating temperature of the conventional solid oxide fuel cell. The detailed configuration of the electrolyte membrane 21 and the process for forming the electrolyte membrane 21 correspond to the main part of the present invention and will be described in detail later.

  The cathode electrode 24 is a metal layer formed on the electrolyte membrane 21 and is formed of a noble metal having catalytic activity that promotes an electrochemical reaction. In this embodiment, the cathode electrode 24 is made of Pd. In the case where the cathode electrode 24 is composed of other types of noble metals that do not have hydrogen permeability, such as platinum (Pt), the cathode electrode 24 is formed outside the cathode electrode 24 (oxidizing gas in a single cell) by forming the cathode electrode 24 sufficiently thin. Gas permeability may be ensured between the flow path 32 side) and the electrolyte membrane 21.

  The gas separators 27 and 29 are gas-impermeable members made of a conductive material such as carbon or metal. On the surfaces of the gas separators 27 and 29, predetermined uneven shapes for forming the above-described single-cell in-cell fuel gas flow channel 30 and single-cell in-cell oxidizing gas flow channel 32 are formed. In addition, in the single cell 20 of the present embodiment shown in FIG. 1, there is a modification such as disposing a member (current collector) having conductivity and gas permeability between the MEA 40 and the gas separator. Is possible.

  As the fuel gas supplied to the fuel cell, a hydrogen-rich gas obtained by reforming a hydrocarbon-based fuel may be used, or a high-purity hydrogen gas may be used. For example, air can be used as the oxidizing gas supplied to the fuel cell.

B. Production method:
Hereinafter, as a method for manufacturing the single cell 20, a process for manufacturing the MEA 40 including the hydrogen permeable metal layer 22, the electrolyte membrane 21, and the cathode electrode 24 will be described. FIG. 2 is an explanatory diagram showing the manufacturing process of the MEA 40.

  When creating the MEA 40, first, the hydrogen permeable metal layer 22 is prepared (step S100). As described above, the hydrogen permeable metal layer 22 is a metal in which a metal layer containing Pd or a layer containing a Group 5 metal is used as a base material and a layer containing Pd is provided on at least one surface thereof. Formed as a film. The hydrogen permeable metal layer 22 may be formed to a thickness of several tens of μm (for example, about 40 μm).

  Next, the electrolyte membrane 21 is formed on the hydrogen permeable metal layer 22 prepared in step S100. When the hydrogen permeable metal layer 22 has a structure in which a layer containing Pd is formed on one surface of a substrate composed of a layer containing a Group 5 metal, the electrolyte membrane 21 contains a Group 5 metal. It is formed on the base material side consisting of a layer to be formed. Here, the electrolyte membrane 21 of the present example has a two-layer structure including a first electrolyte layer 25 and a second electrolyte layer 26. FIG. 3 is an explanatory view schematically showing the state of the electrolyte membrane 21 formed on the hydrogen permeable metal layer 22. The first electrolyte layer 25 and the second electrolyte layer 26 constituting the electrolyte membrane 21 are both polycrystalline layers formed by columnar crystals of solid oxide. In each of the first electrolyte layer 25 and the second electrolyte layer 26, the longitudinal direction of the columnar crystals constituting each layer is substantially constant in the layer, and the first electrolyte layer 25 and the second electrolyte layer 26 are Between them, the longitudinal directions of the columnar crystals constituting each layer are different from each other. The electrolyte membrane 21 composed of the first electrolyte layer 25 and the second electrolyte layer 26 is formed by forming a film on the hydrogen permeable metal layer 22 while generating the above-described solid oxide. Specifically, it is formed by PVD that discharges the electrolyte material in one direction from a predetermined vapor deposition source. Examples of PVD that discharges an electrolyte material in one direction from a predetermined vapor deposition source include sputtering, ion plating, and vacuum vapor deposition.

  After step S100, first, the first electrolyte layer 25 is formed on the hydrogen permeable metal layer 22 (step S110). FIG. 4 shows how the first electrolyte layer 25 is formed on the hydrogen permeable metal layer 22. When the first electrolyte layer 25 is formed, film formation is performed in a state where the hydrogen permeable metal layer 22 is inclined at a predetermined angle with respect to an electrolyte material vapor deposition source that releases the electrolyte material in one direction. At this time, at the time of film formation by PVD, sufficient energy is given for crystallization of the electrolyte material which is a film formation material. The energy for crystallization of the electrolyte material may be given by heating the hydrogen permeable metal layer 22 as a substrate, or by adjusting the input energy when the electrolyte material collides with the substrate. good. By forming the film while providing energy required for crystallization of the film forming material in this way, crystal grains grow from the surface of the hydrogen permeable metal layer 22 toward the electrolyte material deposition source side, and the discharge direction of the electrolyte material is changed. A first electrolyte layer 25 made of columnar crystals in the longitudinal direction is obtained. In this embodiment, the first electrolyte layer 25 is formed so that the thickness of the first electrolyte layer 25 is the length of the columnar crystal in the longitudinal direction by sufficiently giving the energy required for the crystallization. Thus, the 1st electrolyte layer 25 which is a polycrystalline body which has a crystal grain boundary in the direction corresponding to the discharge direction of electrolyte material is formed.

  Thereafter, the second electrolyte layer 26 is formed on the first electrolyte layer 25 (step S120). FIG. 5 shows how the second electrolyte layer 26 is formed on the first electrolyte layer 25. The second electrolyte layer 26 is formed in the same manner as the first electrolyte layer 25. In step S120, the hydrogen permeable metal layer 22 is formed at an angle different from that in step S110 with respect to the electrolyte material deposition source. In step S120, as in step S110, sufficient energy is given to crystallize the electrolyte material. As a result, crystal grains grow from the surface of the first electrolyte layer 25 toward the electrolyte material deposition source side, and a second electrolyte layer 26 made of columnar crystals with the discharge direction of the electrolyte material as the longitudinal direction is obtained. The second electrolyte layer 26 is also formed by giving a sufficient crystallization energy so that the thickness of the second electrolyte layer 26 is the length of the columnar crystal in the longitudinal direction. At this time, in step S110 and step S120, since the angle of the hydrogen permeable metal layer 22 with respect to the electrolyte material deposition source is different, the columnar crystals constituting the first electrolyte layer 25 and the second electrolyte layer 26 respectively. Are formed in different directions, that is, the directions of crystal grain boundaries formed over the thickness direction of each layer. In addition, the thickness of each of the first electrolyte layer 25 and the second electrolyte layer 26 can be set to, for example, 0.05 to 3 μm.

  Thereafter, the cathode electrode 24 is further formed on the second electrolyte layer 26 (step S130), and the MEA 40 is completed. The cathode electrode 24 can be a porous film formed by PVD such as sputtering, ion plating, or vacuum deposition. The thickness of the cathode electrode 24 is preferably 1 μm or less, for example.

  When assembling the fuel cell, the gas separators 27 and 29 are disposed so as to sandwich the MEA 40 manufactured according to FIG. 2 to form a single cell 20, and a predetermined number of the single cells 20 are stacked.

  According to the fuel cell manufacturing method configured as described above, each layer included in the electrolyte membrane 21 is formed by columnar crystals whose longitudinal directions are aligned in a substantially constant direction, and the longitudinal directions of the columnar crystals are adjacent to each other. Due to the difference, when a crack is generated in the electrolyte membrane 21, the generated crack is bent along the crystal grain boundary. This is because when some stress acts on the electrolyte membrane to cause a crack, the crack mainly occurs along the crystal grain boundary. Therefore, when a crack occurs in the electrolyte membrane 21, the crack penetrates the electrolyte membrane in the thickness direction as compared with a case where a crack occurs in the electrolyte membrane having a crystal grain boundary having a relatively straight shape in the thickness direction. It becomes difficult. Further, even when a crack occurs through the electrolyte membrane, when the conductive material enters the generated crack, the penetration of the conductive material into the crack is hindered by the crack shape. It is suppressed that the conductive material reaches the hydrogen permeable metal layer 22. For example, when a crack occurs in the electrolyte membrane 21 during the manufacture of the MEA 40, the electrode material for forming the cathode electrode 24 can be prevented from entering the crack. In addition, when a crack occurs in the electrolyte membrane 21 during the operation of the fuel cell, the electrode material (metal constituting the hydrogen permeable metal layer 22 and the cathode electrode 24) softened by heating during operation is inside the crack. Flowing is suppressed. Thus, a short circuit between the electrodes through the generated crack can be suppressed.

  In FIGS. 4 and 5, the hydrogen permeable metal layer 22 is swung with respect to the electrolyte material deposition source so that the angle of the hydrogen permeable metal layer 22 with respect to the electrolyte material deposition source varies. Represents. As described above, when the angle of the hydrogen permeable metal layer 22 with respect to the electrolyte material vapor deposition source is changed, the hydrogen permeable metal layer 22 is further rotated with respect to the electrolyte material vapor deposition source, so that it can be viewed from any direction. However, in the first electrolyte layer 25 and the second electrolyte layer 26, it is preferable to form the electrolyte membrane 21 so that the directions of crystal grain boundaries formed over the thickness direction of each layer are different from each other.

C. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

C1. Modification 1:
In the embodiment, the electrolyte membrane 21 is formed by two electrolyte layers, but may be formed by three or more electrolyte layers. Also in this case, the same effect can be obtained if the directions of grain boundaries formed in the thickness direction of the electrolyte layer are different between adjacent electrolyte layers.

C2. Modification 2:
Moreover, each electrolyte layer which comprises the electrolyte membrane 21 may be formed into a film by methods other than PVD, for example, spraying, and the direction of the grain boundary formed in the thickness direction should just differ between each electrolyte layer. Moreover, as long as the direction of the grain boundary formed over the thickness direction of an electrolyte layer differs between adjacent electrolyte layers, you may form into a film by a different method for every electrolyte layer.

C3. Modification 3:
In the adjacent electrolyte layers having different grain boundary directions formed over the thickness direction of the electrolyte layer, the type of solid oxide constituting each layer may be different. For example, the second electrolyte layer 26 is formed of a BaCeO ₃ solid oxide having high proton conductivity, and the first electrolyte layer 25 in contact with the hydrogen permeable metal layer 22 is more than the BaCeO ₃ solid oxide. It can be formed of a solid oxide such as SrZrO ₃ or CaZrO ₃ which has high chemical stability and low reactivity to the catalyst metal.

C4. Modification 4:
In the embodiment, the cathode electrode 24 is formed by PVD, but may be formed by other film forming methods such as thermal spraying. Alternatively, the cathode electrode 24, which is a porous electrode, may be formed by applying a conductive paste, which is an electrode material containing a catalytic metal, onto the electrolyte membrane 21, followed by drying and firing. Whichever method is used, when a crack occurs in the electrolyte membrane 21 during the production of the fuel cell (when the cathode electrode is formed), the crack is formed in a shape bent along the crystal grain boundary. It is possible to suppress the electrode material from entering the crack and reaching the hydrogen permeable metal layer 22 side. Thereby, a short circuit between the cathode electrode and the hydrogen permeable metal layer 22 via the electrolyte membrane 21 can be prevented.

C5. Modification 5:
In the embodiment, the cathode electrode 24 is formed of a noble metal, but may be formed of a material other than a noble metal or a material other than a metal. For example, the cathode electrode 24 can be formed of a mixed conductor having proton conductivity and electron conductivity. As such a mixed conductor, for example, a SrZrO ₃ -based or BaCeO ₃ -based solid oxide or tungsten oxide (WO ₃ ) can be used. Further, the cathode electrode 24 can be formed of a mixed conductor having oxide ion conductivity and electron conductivity. As such a mixed conductor, for example, a BaPrCoO ₃ -based solid oxide can be used. Each of the solid oxides can exhibit electronic conductivity in addition to ionic conductivity by adjusting the composition of the constituent elements. When any material is used to form the cathode electrode 24, the electrode material can be prevented from entering the cracks of the electrolyte membrane 21 and reaching the hydrogen permeable metal layer 22 side. A short circuit between the interposed cathode electrode and the hydrogen permeable metal layer 22 can be prevented.

C6. Modification 6:
In the embodiment, the hydrogen permeable metal layer 22 serving as a base material for forming the electrolyte membrane 21 is arranged on the anode side, but the arrangement on the anode side and the arrangement on the cathode side may be interchanged. That is, the hydrogen permeable metal layer 22 may be used as a cathode electrode of a fuel cell, and an anode electrode may be formed on the electrolyte membrane 21. In this case, a catalyst layer may be further provided on the cathode side of the hydrogen permeable metal layer 22. Note that a fuel cell using a dense hydrogen permeable metal layer 22 formed of a gas permeable metal film as a base material for forming the electrolyte membrane 21 has hydrogen permeability when a crack occurs in the electrolyte film 21. The metal layer 22 further provides an effect of suppressing cross leak between the fuel gas and the oxidizing gas via the electrolyte membrane 21.

  The present invention is also applicable to the case where a substrate other than a metal film such as the hydrogen permeable metal layer 22 is used as the substrate for forming the electrolyte membrane 21. For example, an electrode member made of a porous material may be used as a base material, and an electrolyte membrane similar to that of the example may be formed on the porous electrode member. Also in this case, the same effect of preventing a short circuit through the electrolyte membrane can be obtained by changing the direction of the grain boundary in each layer constituting the electrolyte membrane.

C7. Modification 7:
The solid oxide constituting the electrolyte membrane may be a proton conductive solid oxide other than the perovskite type, such as a pyrochlore or spinel type solid oxide. Alternatively, the present invention can be applied not only to proton conductive solid oxides but also to fuel cells using solid oxides having oxide ion conductivity. Further, each electrolyte layer constituting the electrolyte membrane may be formed of an electrolyte other than the solid oxide. Any electrolyte having a crystal structure and capable of changing the grain boundary direction (crystal growth direction) for each electrolyte layer may be used. In either case, the same effect can be obtained by forming electrolyte membranes by stacking electrolyte layers having different grain boundary directions formed across the thickness direction of the electrolyte layer.

2 is a schematic cross-sectional view illustrating an outline of a configuration of a single cell 20. FIG. It is explanatory drawing showing the manufacturing process of MEA40. It is explanatory drawing which represents the mode of the electrolyte membrane 21 which has a two-layer structure typically. FIG. 6 is an explanatory diagram illustrating a state in which a first electrolyte layer 25 is formed. FIG. 6 is an explanatory diagram illustrating a state in which a second electrolyte layer 26 is formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Single cell 21 ... Electrolyte membrane 22 ... Hydrogen-permeable metal layer 24 ... Cathode electrode 25 ... 1st electrolyte layer 26 ... 2nd electrolyte layer 27, 29 ... Gas separator 30 ... Fuel gas flow path in a single cell 32 ... Single cell Inner oxidizing gas flow path 40 ... MEA

Claims (19)

A method for producing an electrolyte membrane for a fuel cell, comprising:
(A) forming a first layer of the first electrolyte by growing a crystal of the first electrolyte in a certain direction;
(B) a second layer made of the second electrolyte by growing a crystal of the second electrolyte on the first layer in a specific direction different from the growth direction of the crystal in the first layer. A process for producing an electrolyte membrane for a fuel cell, comprising: A method for producing an electrolyte membrane for a fuel cell according to claim 1, further comprising:
(C) Growing a predetermined electrolyte crystal on a plurality of previously formed layers made of the electrolyte crystal in a direction different from the crystal growth direction in the uppermost layer of the plurality of already formed layers. Forming another layer of the predetermined electrolyte,
A method for producing a fuel cell, wherein the step (c) is performed once or more. A method for producing an electrolyte membrane for a fuel cell according to claim 1 or 2,
The step of forming each of the layers includes the step of forming the material from a direction corresponding to a direction in which the crystal is grown with respect to a predetermined base material while providing energy capable of crystallizing the material forming the electrolyte layer. A method for producing an electrolyte membrane for a fuel cell to be released. A method for producing an electrolyte membrane for a fuel cell according to claim 3,
Said (a) process and (b) process are performed by PVD. The manufacturing method of the electrolyte membrane for fuel cells. A method for producing an electrolyte membrane for a fuel cell according to any one of claims 1 to 4,
The process of forming each layer which comprises the said electrolyte membrane grows the crystal | crystallization of the same kind of electrolyte. The manufacturing method of the electrolyte membrane for fuel cells. A method for producing an electrolyte membrane for a fuel cell according to any one of claims 1 to 5,
The process of forming each layer which comprises the said electrolyte membrane grows the crystal | crystallization of a solid oxide. The manufacturing method of the electrolyte membrane for fuel cells. A fuel cell manufacturing method comprising:
(A) preparing a conductive base material for constituting the fuel cell;
(B) forming an electrolyte membrane on the substrate;
The step (b)
(B-1) forming a first layer of the first electrolyte by growing a crystal of the first electrolyte in a certain direction on the substrate;
(B-2) A second electrolyte made of the second electrolyte is grown on the first layer by growing a second electrolyte crystal in a specific direction different from the crystal growth direction in the first layer. Forming a layer of the fuel cell. A method of manufacturing a fuel cell according to claim 7,
The step (b) further includes
(B-3) Growing a predetermined electrolyte crystal in a direction different from the crystal growth direction in the uppermost layer of the plurality of already formed layers on the plurality of already formed layers made of the electrolyte crystals. A step of forming another layer of the predetermined electrolyte,
A method for producing a fuel cell, wherein the step (b-3) is performed once or more. A method for producing a fuel cell according to claim 7 or 8,
The step of forming each layer in the step (b) includes the step of forming the electrolyte layer from a direction corresponding to a direction in which the crystal is grown with respect to the base material while giving energy capable of crystallization. A method of manufacturing a fuel cell that releases material. A method of manufacturing a fuel cell according to claim 9,
The step of forming each layer in the step (b) is performed by PVD. A method of manufacturing a fuel cell according to any one of claims 7 to 10,
The step of forming each layer constituting the electrolyte membrane grows the same type of electrolyte crystal. A method for producing a fuel cell according to any one of claims 7 to 11,
The process of forming each layer which comprises the said electrolyte membrane grows the crystal | crystallization of a solid oxide. The manufacturing method of a fuel cell. A method of manufacturing a fuel cell according to any one of claims 7 to 12, further comprising:
(C) A method for producing a fuel cell, comprising a step of forming an electrode using a conductive material on the electrolyte membrane. A method of manufacturing a fuel cell according to any one of claims 7 to 13,
The base material is a hydrogen permeable metal film. An electrolyte membrane for fuel cells formed by electrolyte crystals,
A plurality of layers in which layers of crystal grain boundaries formed in the thickness direction are aligned in a certain direction, and a plurality of adjacent layers have different crystal grain boundary directions formed in each layer. An electrolyte membrane for a fuel cell. The fuel cell electrolyte according to claim 15,
Each of the layers is a layer formed by columnar crystals of the electrolyte, and the longitudinal direction of the columnar crystals is aligned in a certain direction.
In adjacent layers, the longitudinal directions of the columnar crystals are different from each other. Electrolyte membrane for fuel cell. The fuel cell electrolyte according to claim 15 or 16,
The electrolyte is a solid oxide. Fuel cell electrolyte membrane. A fuel cell,
An electrolyte membrane for a fuel cell according to any one of claims 15 to 17,
A fuel cell comprising: an electrode formed adjacent to the electrolyte membrane and formed of a metal. The fuel cell according to claim 18, wherein
The fuel is a hydrogen permeable metal.

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