JP2008034290A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of efficiently supplying oxygen to an oxidant electrode, discharging water from near the oxidant electrode and improving output. <P>SOLUTION: With this fuel cell, oxygen can be efficiently supplied to the oxidant electrode 4 through a granular structure of a material including ceria (cerium oxide (CeO<SB>2</SB>)) structuring an oxygen permeable layer 5. The water near the oxidant electrode 4 can be discharged through grain boundary of the material including ceria. Thus, a permeating route of oxygen and a water discharge route can be separated by using this oxygen permeable layer 5 and it is possible to inhibit water discharge from hindering oxygen permeation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell having a fuel electrode, an electrolyte membrane, and an oxidant electrode.

  A fuel cell is a generator that generates electricity by supplying a hydrogen-containing gas, an organic alcohol, or the like and a gas containing oxygen to an electrode. Hydrogen is oxidized on the electrode, and hydrogen ions conduct through the electrolyte and move to the oxidant electrode side. On the oxidizer electrode side, the supplied oxygen and the moving hydrogen ions react to generate water. Moreover, electrons generate electrical energy by circulating through an external circuit.

  The fuel cell is attracting attention as a clean power generation system because it has less burden on the environment of the waste generated by power generation. Among fuel cells, a polymer electrolyte fuel cell using a polymer electrolyte membrane having a hydrogen ion conductor as an electrolyte is currently proposed for use as a mobile power source for space, vehicles, and the like.

  The conventional fuel cell shown in FIG. 5 is, for example, a solid polymer fuel cell as disclosed in Japanese Patent Laid-Open No. 2003-86192 (Patent Document 1). The fuel cell includes a power generation element 113 that includes a fuel electrode 110, an oxidant electrode 111, and an electrolyte membrane 112 sandwiched between the fuel electrode 110 and the oxidant electrode 111.

  Channel plates 116 and 117 are disposed on both sides of the power generation element 113, respectively, and a fuel channel 114 and an oxidant channel 115 are formed on both sides of the power generation element 113. The polymer electrolyte membrane 112 used in the solid polymer fuel cell as shown in FIG. 5 exhibits high proton conductivity by containing water in the membrane. For this reason, in order for the electrolyte membrane 112 to maintain proton conductivity, the electrolyte membrane 112 needs to contain water.

  However, if the water generated by the power generation reaction of the power generation element 113 stays in the vicinity of the oxidant electrode 111, the supply of oxygen to the oxidant electrode 111 is hindered. Therefore, the water in the vicinity of the oxidant electrode 111 must be quickly discharged.

  Therefore, in this conventional example, as shown in FIG. 5, the gas diffusion layer 119 is sandwiched between the oxidant electrode 111 and the oxidant flow path 115, and the oxidant flow path 115 passes through the gas diffusion layer 119. Oxygen is supplied to the oxidant electrode 111 and water is discharged from the vicinity of the oxidant electrode 111 to the oxidant channel 115. The gas diffusion layer 119 is formed of a porous material such as carbon fiber.

However, in the fuel cell of the conventional example shown in FIG. 5, gas diffusion from the oxidant flow path 115 due to the fact that water near the oxidant electrode 111 is discharged to the oxidant flow path 115 through the gas diffusion layer 119. Oxygen supply to the oxidant electrode 111 via the layer 119 is hindered. For this reason, the output of the fuel cell is reduced, and there is a problem that the output of the fuel cell is not improved even if the supply amount of the oxidant to the oxidant flow path 115 is increased.
JP 2003-86192 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell that can efficiently supply oxygen to an oxidant electrode and discharge water from the vicinity of the oxidant electrode to improve output.

In order to solve the above problems, a fuel cell according to the present invention is provided with a fuel electrode that is supplied with liquid fuel and generates cations and electrons from the liquid fuel;
An electrolyte membrane disposed to face the fuel electrode and permeable to cations from the fuel electrode;
An oxidant electrode that is disposed so as to face the electrolyte membrane while being supplied with the oxidant, and reacts the cation that has passed through the electrolyte membrane and the oxidant;
A first flow path plate disposed to face the fuel electrode and forming a first flow path for supplying the liquid fuel to the fuel electrode;
A second flow path plate which is disposed so as to face the oxidant electrode and forms a second flow path for supplying the oxidant to the oxidant electrode;
An oxygen permeable layer is provided between the oxidant electrode and the second flow path plate and made of a material having oxygen permeability.

  According to the fuel cell of the present invention, the oxygen permeable layer disposed between the oxidant electrode and the second flow path plate is made of a material having oxygen permeability. Therefore, oxygen can be efficiently supplied from the second channel to the oxidant electrode through the oxygen permeable layer, and water near the oxidant electrode can be discharged through the oxygen permeable layer.

  In one embodiment, the material having oxygen permeability contains at least ceria.

According to the fuel cell of this embodiment, oxygen can be more efficiently supplied to the oxidant electrode through the grain structure of the material containing ceria (cerium oxide (CeO ₂ )) constituting the oxygen permeable layer. Further, water near the oxidizer electrode can be discharged through the grain boundary of the material containing ceria in the oxygen permeable layer. Therefore, according to this oxygen permeable layer, the oxygen permeation path and the water discharge path can be separated, and the water discharge can be inhibited from inhibiting the oxygen permeation.

  In one embodiment, the oxygen permeable material includes at least a solid solution of ceria and zirconia.

According to the fuel cell of this embodiment, since the oxygen permeable layer was made of a material containing a solid solution of ceria (cerium oxide (CeO ₂ )) and zirconia (ZrO ₂ ), the oxygen permeable layer was passed through the oxygen permeable layer to the oxidant electrode. Oxygen can be supplied more efficiently.

  In one embodiment, the grain structure of the oxygen permeable layer is a columnar structure.

  According to the fuel cell of this embodiment, since the grain structure of the oxygen permeable layer is a columnar structure, supply of oxygen from the second flow path to the oxidant electrode and discharge of water from the vicinity of the oxidant electrode Can be performed efficiently.

  Moreover, in the fuel cell of one embodiment, the average grain size of the columnar structure of the oxygen permeable layer is 5 nm or more.

  According to the fuel cell of this embodiment, since the average grain size of the columnar structure of the oxygen permeable layer is 5 nm or more, oxygen is supplied from the second channel to the oxidant electrode through the oxygen permeable layer of the columnar structure. Can be supplied efficiently. When the average grain size of the columnar structure of the oxygen permeable layer is less than 5 nm, the oxygen transmission performance by the oxygen permeable layer is significantly reduced.

  In one embodiment, the average grain size of the columnar structure of the oxygen permeable layer is 1000 nm or less.

  According to the fuel cell of this embodiment, since the average grain size of the columnar structure of the oxygen permeable layer is 1000 nm or less, the oxygen permeable performance can be ensured without significantly reducing the water discharging performance. In addition, when the average grain size of the columnar structure of the oxygen permeable layer exceeds 1000 nm, the water discharging performance with respect to the oxygen permeable performance of the oxygen permeable layer is significantly lowered.

  In one embodiment, the oxygen permeable layer has a thickness of 50 nm or more and 5000 nm or less.

  According to the fuel cell of this embodiment, since the layer thickness of the oxygen permeable layer is 5000 nm or less, oxygen can be efficiently supplied from the second channel to the oxidant electrode through the columnar structure oxygen permeable layer. In addition, when the layer thickness of the oxygen permeable layer exceeds 5000 nm, the water discharging performance is remarkably lowered as compared with the oxygen permeable performance. When the thickness of the oxygen permeable layer is less than 50 nm, it is difficult to obtain a layer having a desired columnar structure.

  In one embodiment, the crystal growth orientation of the columnar structure of the oxygen permeable layer includes <100>.

  According to the fuel cell of this embodiment, since the crystal structure of the oxygen permeable layer is uniform, uniform oxygen permeable performance can be obtained.

  In one embodiment, the crystal growth orientation of the columnar structure of the oxygen permeable layer includes <110> and <111>.

  According to the fuel cell of this embodiment, the grain boundary ratio of the ceria layer in the oxygen permeable layer is higher than that in the case where the crystal growth orientation of the columnar structure of the oxygen permeable layer is <100> single orientation. Can be increased. Therefore, oxygen can be more efficiently supplied to the oxidant electrode through the oxygen permeable layer.

  In one embodiment, the crystal growth orientation of the columnar structure of the oxygen permeable layer includes <111>.

  According to the fuel cell of this embodiment, a larger oxygen permeable surface can be secured as compared with the case where the crystal growth orientation of the columnar structure of the oxygen permeable layer is the <100> orientation.

  In one embodiment, the substrate on which the power generating element is formed is an yttrium-stabilized zirconia substrate.

  According to the fuel cell of this embodiment, the substrate on which the power generating element is formed is a thin film substrate having a thickness of, for example, about 50 μm, and oxygen permeation is performed on the thin film substrate using ceria (or a solid solution of ceria and zirconia) as a material. The layer can be formed at a high temperature.

  In one embodiment, the oxidant electrode is a ruthenium oxide film.

  According to the fuel cell of this embodiment, the oxidant electrode is also used as a base for a material to be formed at a high temperature such as ceria (or a solid solution of ceria and zirconia) as a material for forming an oxygen permeable layer. be able to.

  According to the fuel cell of the present invention, the oxygen permeable layer disposed between the oxidant electrode and the second flow path plate is made of a material having oxygen permeability. Therefore, oxygen can be efficiently supplied from the second channel to the oxidant electrode through the oxygen permeable layer, and water near the oxidant electrode can be discharged through the oxygen permeable layer.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a sectional view showing a layer structure of an embodiment of a fuel cell according to the present invention. This embodiment includes a fuel electrode 2, an electrolyte membrane 3 disposed to face the fuel electrode 2, and an oxidant electrode 4 disposed to face the electrolyte membrane 3 on the opposite side of the fuel electrode 2. . The fuel electrode 2, the electrolyte membrane 3, and the oxidant electrode 4 constitute a power generation element. The fuel cell also has a fuel flow path plate 1 that is disposed so as to face the fuel electrode 2 and forms a fuel flow path 11 that supplies liquid fuel to the fuel electrode 2. The fuel flow path plate 1 is a first flow path plate, and the fuel flow path 11 is a first flow path.

  The fuel electrode 2 is made of a resin layer containing a metal catalyst. As this metal catalyst, a platinum-ruthenium alloy or the like is used as an example, but other alloys such as platinum and gold, platinum and osmium, platinum and rhodium can be used. Further, as the resin layer of the fuel electrode 2, for example, a perfluoroalkyl sulfonic acid resin is used.

  The material of the electrolyte membrane 3 may be, for example, an organic material or an inorganic material as long as it is a proton-conductive heat-resistant and acid-resistant material. Here, a sulfonic acid having an organic fluorine-containing polymer as a skeleton is used. A group-containing perfluorocarbon (Nafion 117 (manufactured by DuPont) (registered trademark)) is used. The electrolyte membrane 3 only needs to have a proton-conducting function, and may be one in which the electrolyte membrane is embedded in another base material.

  Further, as the fuel flow path plate 1, a substrate that is not permeable to liquid fuel, such as a metal, a silicon substrate, a glass substrate, and a resin substrate, can be used, but here, a nickel plate that has been subjected to fine processing is used.

  A diffusion layer 7 is disposed between the fuel flow path plate 1 and the fuel electrode 2. As the diffusion layer 7, a porous material such as carbon paper, a sintered body of carbon, a sintered metal such as nickel, or a foam metal can be used.

  The fuel cell further includes an oxidant flow path plate 6 that is disposed so as to face the oxidant electrode 4 and that forms an oxidant flow path 12 that supplies the oxidant electrode 4 with an oxidant. The oxidant channel plate 6 is a second channel plate, and the oxidant channel 12 is a second channel. A diffusion layer 8 is disposed between the oxidant flow path plate 6 and the oxidant electrode 4.

  As the diffusion layer 8, a porous material such as carbon paper, a sintered body of carbon, a sintered metal such as nickel, and a foamed metal can be used in the same manner as the diffusion layer 7 on the fuel electrode 2 side. The oxidant electrode 4 is made of a resin layer containing a metal catalyst, like the fuel electrode 2.

Further, this embodiment includes an oxygen permeable layer 5 that is disposed between the oxidant electrode 4 and the diffusion layer 8 and made of a material having oxygen permeability. In this embodiment, a material containing ceria (cerium oxide) is used as an example of a material having oxygen permeability for forming the oxygen permeable layer 5. A typical composition of this ceria is CeO ₂ , but CeO ₂ crystals have a property of allowing oxygen to pass through the crystal structure. As shown in the reference (R & D Review of Toyota CRDL Vol. 37 No.4 pp.1-5), the CeO ₂ crystal absorbs oxygen from the high concentration side and releases the occluded oxygen to the low concentration side. Is known to have

  As shown in this embodiment, by using a material containing ceria as a material having oxygen permeability constituting the oxygen permeable layer 5, the oxygen permeable layer 5 enters the crystal from the oxidant flow path 12 side having a high oxygen concentration. While taking in oxygen, oxygen can be efficiently supplied to the oxidant electrode 4 side having a low oxygen concentration.

  In the fuel cell of this embodiment, for example, a mixture of methanol and water is supplied into the fuel flow path 11 as a liquid fuel. This liquid fuel is supplied from the fuel flow path 11 to the diffusion layer 7 adjacent to the fuel electrode 2, diffuses and permeates through the diffusion layer 7, reaches the fuel electrode 2, and reacts, thereby cation (H +), electrons and Carbon dioxide is generated as exhaust gas. The cation (H +) reaches the oxidant electrode 4 via the electrolyte membrane 3. On the other hand, the electrons are guided from the fuel electrode 2 to the oxidant electrode 4 via an external circuit (not shown). Further, the carbon dioxide generated by the fuel electrode 2 diffuses in the diffusion layer 7 and is discharged from an outlet (not shown).

  On the other hand, oxygen as an example of the oxidant introduced from the oxidant flow path 12 diffuses into the diffusion layer 8 and permeates through the material containing ceria in the oxygen permeable layer 5 as illustrated in FIG. , And supplied to the oxidant electrode 4. The oxygen reacts with cations (H +) and electrons from the fuel electrode 2 at the oxidizer electrode 4 to produce water. As illustrated in FIG. 2, this water diffuses through the grain boundary of the material containing ceria in the oxygen permeable layer 5, diffuses in the diffusion layer 8, and is discharged from an outlet (not shown).

  Thus, according to this embodiment, the oxygen permeation path and the water discharge path in the oxygen permeable layer 5 can be separated, and the discharge of water can be inhibited from inhibiting the permeation of oxygen. Therefore, according to this embodiment, oxygen can be efficiently supplied to the oxidant electrode 4 and water can be discharged from the vicinity of the oxidant electrode 4 to improve the output.

In the above embodiment, ceria having a crystal structure of CeO ₂ (cerium oxide) is used as the material having oxygen permeability constituting the oxygen permeable layer 5, but ceria and zirconia are used as the material having oxygen permeability. A solid solution may be used. CeO ₂ —ZrO ₂ or Ce _1-X Zr _X O ₂ has oxygen permeability like the CeO ₂ crystal. Therefore, even when the oxygen permeable layer 5 is made of a material containing a solid solution of ceria and zirconia, the same effect as in the above embodiment can be obtained. Furthermore, by changing the solid solution ratio of ceria and zirconia, the lattice constant of the solid solution can be changed and the oxygen permeation performance can be changed. Therefore, the oxygen permeation layer having different oxygen permeability according to the operating state of the fuel cell. 5 is obtained.

  Further, in the oxygen permeable layer 5 made of the material containing ceria or the material containing a solid solution of ceria and zirconia, when the grain structure of the oxygen permeable layer 5 is a columnar structure, the oxidant electrode is connected to the oxidant channel 12. It is possible to more efficiently supply oxygen to 4 and discharge water from the vicinity of the oxidant electrode 4 to the diffusion layer 8.

  Further, in the oxygen permeable layer 5 in which the grain structure made of the material containing ceria or the material containing a solid solution of ceria and zirconia is a columnar structure, if the average grain size of the columnar structure is 5 nm or more, the oxidizing agent Oxygen can be efficiently supplied from the flow path 12 to the oxidant electrode 4 through the oxygen-permeable layer 5 having the columnar structure. When the average grain size of the columnar structure of the oxygen permeable layer 5 is less than 5 nm, the oxygen transmission performance by the oxygen permeable layer 5 is significantly reduced.

  In addition, if the average grain size of the columnar structure of the oxygen permeable layer 5 is set to 1000 nm or less, the oxygen permeable performance can be ensured without significantly reducing the water discharging performance. In addition, when the average grain size of the columnar structure of the oxygen permeable layer 5 exceeds 1000 nm, the water discharging performance with respect to the oxygen permeable performance by the oxygen permeable layer 5 is remarkably lowered.

  When the layer thickness of the oxygen-permeable layer 5 having the columnar structure is 5000 nm or less, oxygen can be efficiently supplied from the oxidant channel 12 to the oxidant electrode 4 through the oxygen-permeable layer 5. In addition, when the layer thickness of the oxygen permeable layer 5 exceeds 5000 nm, the water discharge performance is remarkably reduced as compared with the oxygen transmission performance.

  Further, when the crystal growth orientation of the columnar structure of the oxygen permeable layer 5 includes <100>, the crystal structure of the oxygen permeable layer 5 is uniform, so that uniform oxygen transmission performance can be obtained. In addition, when the crystal growth orientation of the columnar structure of the oxygen permeable layer 5 includes <111>, the crystal growth orientation of the columnar structure of the oxygen permeable layer 5 is <100> single orientation. The grain boundary ratio of the ceria layer in the oxygen permeable layer 5 can be increased. Therefore, oxygen can be more efficiently supplied to the oxidizer electrode 4 through the oxygen permeable layer 5. Further, when the crystal growth orientation of the columnar structure of the oxygen permeable layer 5 includes <110>, compared to the case where the crystal growth orientation of the columnar structure of the oxygen permeable layer 5 is a <100> orientation, A large oxygen permeable surface can be secured.

  Next, an example of a method of manufacturing the fuel cell according to the above embodiment will be described with reference to FIGS. 3A to 3D and FIGS. 4A to 4C in order.

  First, as shown in FIG. 3A, as the base substrate 20, for example, an yttrium-stabilized zirconia substrate (hereinafter referred to as a YSZ substrate) is used. Since this YSZ substrate is excellent in heat resistance, a material such as ceria or a solid solution of ceria and zirconia can be formed on the base substrate 20 at a high temperature even if the thickness is about 50 μm. It becomes. A ruthenium oxide film 24 as an oxidant electrode is formed on the base substrate 20 by a known sputtering method. Since the ruthenium oxide film 24 is conductive and excellent in heat resistance, it also serves as a base for a material to be formed at a high temperature such as ceria or a solid solution of ceria and zirconia.

Next, as shown in FIG. 3B, a thin film layer (oxygen permeable layer) made of a material having oxygen permeability by, for example, a known pulse laser deposition method (hereinafter referred to as PLD method) over the entire surface of the ruthenium oxide film 24. As a result, a 300 nm ceria layer 25 is formed. By maintaining the oxygen pressure in the film formation chamber at the time of forming the ceria layer 25 at 7 Pa or more, the ceria layer 25 having a columnar CeO ₂ is obtained. As a result, the structure can penetrate the crystal grains and grain boundaries of the ceria layer 25 in the film thickness direction, so that it is possible to efficiently supply oxygen and discharge water as described above. The grain size of the columnar CeO ₂ crystal can be further reduced by lowering the pressure during the formation of the ceria layer 25, but the average grain size is preferably 5 nm or more. The reason is that when the average grain size of the columnar structure CeO ₂ crystal is less than 5 nm, the ratio of grain boundaries becomes too large, and the oxygen permeation performance deteriorates.

On the other hand, by increasing the pressure at the time of forming the ceria layer 25, the average grain size of the columnar structure CeO ₂ crystal can be increased, but the average grain size of the columnar structure CeO ₂ crystal is 5000 nm. The following is preferable. The reason is that when the average grain size of the columnar structure CeO ₂ crystal exceeds 5000 nm, the ratio of the grain boundary becomes too small, and the water discharge performance is lowered as compared with the oxygen permeability. The average grain size of the columnar CeO ₂ crystals is more preferably 1000 nm or less.

Further, it is preferable to keep the oxygen pressure in the film formation chamber at the time of forming the ceria layer 25 at 12 Pa. In this case, the grain size of the CeO ₂ crystal is about 10 nm, and the grain boundaries can be densely distributed. Here, the film thickness of the ceria layer 25 having a columnar structure is 300 nm, but the film thickness is not limited to this. However, if the thickness of the ceria layer 25 having a columnar structure exceeds 5000 nm, the grain boundary becomes longer, and the water discharge efficiency is significantly reduced compared to the oxygen permeation performance. Therefore, the thickness of the ceria layer 25 is 5000 nm or less. It is preferable to do.

  After the ceria layer 25 is formed in this way, as shown in FIG. 3C, the back surface of the base substrate 20 that is a YSZ substrate is patterned by a known photolithography method, and the ruthenium oxide film is etched from the back surface 20A of the base substrate 20. The back surface 24A of 24 is exposed. Next, as shown in FIG. 3D, a cation exchange polymer film as an electrolyte film 23 is formed on the exposed back surface 24A of the ruthenium oxide film 24.

  Next, as shown in FIG. 4A, an Au layer as a fuel electrode 22 is formed on the surface of the electrolyte membrane 23.

  Next, as shown in FIG. 4B, a diffusion layer 27 for supplying fuel is formed on both side surfaces of the laminated substrate composed of the fuel electrode 22, the electrolyte membrane 23, the oxidant electrode 24, and the ceria layer 25 thus manufactured. Then, the diffusion layer 28 for supplying the oxidizing agent is bonded. Next, as shown in FIG. 4C, the flow path plates 21 and 26 are joined so as to sandwich the laminated substrate to which the diffusion layers 27 and 28 are joined.

  Thereby, the fuel cell of the structure substantially the same as embodiment shown in FIG. 1 can be manufactured.

  In the fuel cell manufacturing method, the gas diffusion layer 28 for supplying the oxidant is joined to the ceria layer 25. However, in this embodiment, since the grain size of the ceria layer is sufficiently small, the diffusion layer 28 may be omitted. it can.

  In the fuel cell manufacturing method, a (100) plane YSZ single crystal substrate is used as the base substrate 20, and ceria is formed on the <100> -oriented ruthenium oxide film 24 at a deposition temperature of 500 ° C. or higher. Thus, the ceria layer 25 unidirectionally oriented in <100> is obtained. When the ceria layer 25 is unidirectionally oriented to <100>, the crystal structure is uniform, so that uniform oxygen permeation performance can be obtained.

  Further, when ceria is formed on the <100> -oriented ruthenium oxide film 24 at a film formation temperature of 500 ° C. or less, the ceria layer 25 in which <100>, <110>, and <111> orientations are mixed is obtained. Thereby, the grain boundary ratio of the ceria layer 25 can be increased as compared with the case where the single orientation is <100>.

  Further, since a ruthenium oxide film 24 preferentially oriented to <111> is obtained on a polycrystalline YSZ substrate (yttrium stabilized zirconia substrate), the ceria layer 25 formed on this ruthenium oxide film 24 is made <111 > Can be preferentially oriented. When the ceria layer 25 is preferentially oriented to <111>, irregularities are formed on the surface of the ceria layer 25, so that a larger oxygen-permeable surface is ensured than the <100> oriented ceria layer having the same area. Can do.

It is the schematic explaining the structure of embodiment of the fuel cell of this invention. It is a schematic diagram explaining a mode that oxygen and water permeate in oxygen permeable layer 5 of the above-mentioned embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the manufacturing process of the fuel cell of the said embodiment. It is the schematic explaining the structure of the fuel cell of a prior art example.

Explanation of symbols

1 Fuel Channel Plate 2 Fuel Electrode 3 Electrolyte Membrane 4 Oxidant Electrode 5 Oxygen Permeation Layer
6 Oxidant Channel Plate 7 Diffusion Layer for Fuel Supply 8 Diffusion Layer for Oxidant Supply 11 Fuel Channel 12 Oxidant Channel 20 Base Substrate 21 Fuel Channel Plate 22 Fuel Electrode 23 Electrolyte Membrane 24 Ruthenium Oxide Film 25 Ceria Layer 26 Oxidant channel plate 27 Diffusion layer for fuel supply 28 Diffusion layer for oxidant supply

Claims (12)

A fuel electrode that is supplied with liquid fuel and generates cations and electrons from the liquid fuel;
An electrolyte membrane disposed to face the fuel electrode and permeable to cations from the fuel electrode;
An oxidant electrode that is disposed so as to face the electrolyte membrane while being supplied with the oxidant, and reacts the cation that has permeated the electrolyte membrane with the oxidant;
A first flow path plate disposed to face the fuel electrode and forming a first flow path for supplying the liquid fuel to the fuel electrode;
A second flow path plate which is disposed so as to face the oxidant electrode and forms a second flow path for supplying the oxidant to the oxidant electrode;
A fuel cell comprising: an oxygen permeable layer that is disposed between the oxidant electrode and the second flow path plate and made of a material having oxygen permeability. The fuel cell according to claim 1, wherein
The fuel cell characterized in that the material having oxygen permeability contains at least ceria. The fuel cell according to claim 1, wherein
A fuel cell, wherein the oxygen-permeable material includes at least a solid solution of ceria and zirconia. The fuel cell according to claim 2 or 3,
A fuel cell, wherein the grain structure of the oxygen permeable layer is a columnar structure. The fuel cell according to claim 4, wherein
The fuel cell, wherein an average grain size of the columnar structure of the oxygen permeable layer is 5 nm or more. The fuel cell according to claim 4 or 5,
The fuel cell, wherein an average grain size of the columnar structure of the oxygen permeable layer is 1000 nm or less. The fuel cell according to claim 1, wherein
The fuel cell, wherein the oxygen permeable layer has a thickness of 5000 nm or less and 50 nm or more. The fuel cell according to claim 4, wherein
A fuel cell, wherein a crystal growth orientation of the columnar structure of the oxygen permeable layer includes <100>. The fuel cell according to claim 4, wherein
A fuel cell, wherein the crystal growth orientation of the columnar structure of the oxygen permeable layer includes <110> and <111>. The fuel cell according to claim 4, wherein
A fuel cell, wherein a crystal growth orientation of the columnar structure of the oxygen permeable layer includes <111>. The fuel cell according to claim 2, wherein
A fuel cell, wherein the substrate forming the power generation element is an yttrium-stabilized zirconia substrate. The fuel cell according to claim 2, wherein
A fuel cell, wherein the oxidant electrode is a ruthenium oxide film.

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