JP2007188652A - Hydrogen-permeable metal layer-electrolyte complex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a hydrogen-permeable metal layer-electrolyte complex. <P>SOLUTION: This hydrogen-permeable metal layer-electrolyte complex 23 is provided with: a hydrogen-permeable metal layer 22 having a noble metal at least on one surface and selectively making hydrogen permeate therethrough; and an electrolyte layer 21 arranged on the surface of the hydrogen-permeable metal layer 22 having the noble metal, having proton conductivity, and made of a solid oxide. An oxygen-group element other than oxygen is arranged at least on an interfacial surface between the hydrogen-permeable metal layer 22 and the electrolyte layer 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composite of a hydrogen permeable metal layer and an electrolyte.

  As a kind of electrolyte having proton conductivity, an electrolyte made of a solid oxide is known, and such an electrolyte can be used, for example, as an electrolyte layer of a fuel cell. As a fuel cell including an electrolyte layer made of a solid oxide, a fuel cell in which a solid oxide layer having proton conductivity is formed on a hydrogen-permeable metal layer has been proposed (see, for example, Patent Document 1). With such a configuration, the electrolyte layer can be thinned and the proton conductivity in the electrolyte layer can be improved.

JP 2004-146337 A

  However, when using a hydrogen permeable metal layer / electrolyte composite, which is a composite of layers made of different materials, the durability of the composite as a whole is attributed to the different properties of each material. May be damaged. For example, since the thermal expansion coefficient is different between a metal and a solid oxide, stress is generated at the interface between the metal layer and the electrolyte layer due to the difference in the degree of expansion between the metal layer and the electrolyte layer under temperature conditions during operation of the fuel cell. -The durability of the entire electrolyte composite may be impaired. Such a problem can occur not only in a fuel cell but also in other devices using a composite including a hydrogen permeable metal layer and an electrolyte layer made of a solid oxide, such as a hydrogen pump and a hydrogen concentration sensor. It was a problem.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to improve the durability of a hydrogen-permeable metal layer / electrolyte composite.

To achieve the above object, the present invention provides a hydrogen-permeable metal layer / electrolyte composite,
A hydrogen-permeable metal layer that includes a noble metal on at least one surface and selectively transmits hydrogen;
An electrolyte layer comprising a solid oxide having proton conductivity provided on the surface of the hydrogen permeable metal layer provided with the noble metal;
With
The gist is that an oxygen group element other than oxygen is disposed at least at the interface between the hydrogen permeable metal layer and the electrolyte layer.

  According to the hydrogen permeable metal layer / electrolyte composite of the present invention configured as described above, an oxygen group element other than oxygen is present at the interface between the hydrogen permeable metal layer having a noble metal on the surface and the electrolyte layer. By being present, at the interface, a bond between an oxygen group element other than oxygen and a noble metal is formed instead of a bond between oxygen and a noble metal. By adopting such a configuration, the bonding force between the hydrogen permeable metal layer and the electrolyte layer can be increased, and the hydrogen permeation caused by the difference in thermal expansion coefficient between the hydrogen permeable metal layer and the electrolyte layer can be achieved. Damage of the conductive metal layer / electrolyte layer composite can be suppressed, and the durability of the hydrogen permeable metal layer / electrolyte composite can be enhanced.

  In the hydrogen permeable metal layer / electrolyte composite of the present invention, the oxygen group element may be sulfur (S).

  With such a configuration, since the bonding force between sulfur (S) and the noble metal is stronger than the bonding force between oxygen and the noble metal, the durability of the hydrogen permeable metal layer / electrolyte layer composite is improved. Can be increased.

  In the hydrogen permeable metal layer / electrolyte composite of the present invention, the noble metal may be palladium (Pd).

  With such a configuration, since the bonding force between oxygen group elements other than oxygen and palladium (Pd) is stronger than the bonding force between oxygen and palladium (Pd), the hydrogen permeable metal layer -The durability of the electrolyte layer composite can be increased.

  The present invention can be realized in various forms other than the above. For example, the present invention can be realized in the form of a fuel cell, a hydrogen pump, or a hydrogen concentration sensor including the hydrogen permeable metal layer / electrolyte composite according to the present invention. Is possible.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Fuel cell configuration:
B. Production method:
C. Second embodiment:
D. Third embodiment:
E. 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 unit cell 20 includes a hydrogen permeable metal layer / electrolyte complex 23 composed of a hydrogen permeable metal layer 22 and an electrolyte layer 21, a cathode 24 formed on the electrolyte layer 21, and gas separators 27 and 29. ing. 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 24, there is formed an in-single cell oxidizing gas flow path 32 through which an oxidizing gas containing oxygen passes. Hereinafter, a structure including the hydrogen permeable metal layer 22, the electrolyte layer 21, and the cathode 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, and in this embodiment, the hydrogen permeable metal layer 22 is formed of palladium (Pd). In addition to the property of allowing hydrogen to permeate, palladium has an activity of dissociating hydrogen molecules on the surface of the hydrogen permeable metal layer 22 when hydrogen passes through the hydrogen permeable metal layer 22. Such a hydrogen permeable metal layer 22 functions as an anode electrode in the fuel cell. The fuel cell of this example is characterized in that a sulfur (S) element is introduced in the vicinity of the interface including the interface with the electrolyte layer 21 in the hydrogen permeable metal layer 22. Will be described in detail later.

The electrolyte layer 21 is a layer made of a solid electrolyte having proton conductivity. In this embodiment, the electrolyte layer 21 is formed of a perovskite solid oxide. Specifically, for example, the electrolyte layer 21 may be formed of BaCe _0.8 Y _0.2 O ₃ or SrZr _0.8 In _0.2 O ₃ . it can. Since the electrolyte layer 21 is formed on the dense hydrogen permeable metal layer 22, it is possible to sufficiently reduce the thickness. Thus, since the membrane resistance of the electrolyte layer 21 can be reduced by forming the electrolyte layer 21 thinner, the temperature is lower than the operating temperature of the conventional solid electrolyte fuel cell, which is about 200 to 600 ° C. This makes it possible to operate the fuel cell.

  The cathode 24 is a metal layer formed on the electrolyte layer 21 and is formed of a noble metal having catalytic activity that promotes an electrochemical reaction. In this embodiment, the cathode 24 is made of palladium. In the case where the cathode 24 is composed of another kind of noble metal having no hydrogen permeability, such as platinum (Pt), the cathode 24 is formed to be sufficiently thin, etc. Side) and the electrolyte layer 21 may be ensured.

  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 the single cell 20 shown in FIG. 1, between the MEA 40 and the gas separator, a member having conductivity and gas permeability, for example, a metal porous body such as foam metal or metal mesh, carbon paper, etc. It is good also as arrange | positioning a carbon porous body.

  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:
Below, the manufacturing method of the single cell 20 is demonstrated. FIG. 2 is an explanatory diagram showing a manufacturing process of the MEA 40 constituting the single cell 20.

  When creating the MEA 40, first, the hydrogen permeable metal layer 22 is prepared (step S100). In this embodiment, a palladium metal film is prepared as the hydrogen permeable metal layer 22.

Next, sulfur is introduced into one surface of the hydrogen permeable metal layer 22 prepared in step S100, and palladium sulfide (PdS) is formed on the one surface (step S110). That is, a bond between a palladium atom and a sulfur atom is formed. Specifically, palladium sulfide is formed on the hydrogen permeable metal layer 22 by exposing one surface of the hydrogen permeable metal layer 22 to hydrogen sulfide (H ₂ S) gas at 400 ° C.

  Thereafter, an electrolyte layer 21 is formed on the surface of the hydrogen permeable metal layer 22 on which sulfur has been introduced, thereby producing a hydrogen permeable metal layer / electrolyte complex 23 (step S120). The electrolyte layer 21 is formed by forming a film on the hydrogen permeable metal layer 22 while generating the solid oxide described above. As a film forming method, for example, physical vapor deposition (PVD) or chemical vapor deposition (CVD) can be used. Alternatively, the electrolyte layer 21 may be formed by sputtering or sol-gel method. The thickness of the electrolyte layer 21 can be 0.1-5 micrometers, for example.

  As described above, when the electrolyte layer 21 is formed on the hydrogen permeable metal layer 22 into which sulfur is introduced, in the solid oxide having the perovskite crystal structure constituting the electrolyte layer 21, at the interface with the hydrogen permeable metal layer 22. A part of the constituent elements in the solid oxide is combined with sulfur introduced into the hydrogen permeable metal layer 22. Such a state of the interface is schematically shown in FIG. FIG. 3A shows the state of the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 21 in this example, and FIG. 3B shows the state on the hydrogen permeable metal layer 22 into which sulfur is not introduced. The mode that the electrolyte layer 21 was formed is represented. As shown in FIG. 3B, in the case where sulfur is not introduced into the hydrogen permeable metal layer 22, one oxygen atom constituting the electrolyte layer 21 is formed at the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 21. The portion is bonded to palladium constituting the hydrogen permeable metal layer 22. On the other hand, when a sulfur element is introduced into the surface of the hydrogen permeable metal layer 22, sulfur which is the same oxygen group element as oxygen and an element other than oxygen at the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 21. However, in the perovskite crystal structure, at least a part of oxygen is substituted, and a constituent element (represented by A in the figure) in the solid oxide and a sulfur element are combined.

  Thereafter, the cathode 24 is formed on the electrolyte layer 21 (step S130), and the MEA 40 is completed. The cathode 24 can be formed by, for example, PVD or CVD.

  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 of the first embodiment configured as described above, oxygen, which is an oxygen group element, is present at the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 21. Instead of the bond with palladium, a bond between sulfur and palladium is formed. Here, the bond strength between the atoms is stronger in the hydrogen permeable metal layer 22 because the bond strength between the sulfur atom and the palladium atom is stronger than the bond strength between the oxygen atom and the palladium atom. By introducing sulfur into the vicinity of the interface, the bonding force between the hydrogen permeable metal layer 22 and the electrolyte layer 21 can be increased. In this way, by increasing the bonding force between the hydrogen permeable metal layer 22 and the electrolyte layer 21, the hydrogen permeable metal resulting from the difference in thermal expansion coefficient between the hydrogen permeable metal layer 22 and the electrolyte layer 21. The damage of the layer / electrolyte complex 23 can be suppressed, and the durability of the fuel cell can be enhanced.

  Note that the bonding force between the sulfur atom and the palladium atom is stronger than the bonding force between the oxygen atom and the palladium atom, for example, the heat of formation of palladium sulfide (PdS) and palladium oxide (PdO). You can know from the size of. The heat of formation refers to the heat of reaction when 1 mol of a certain compound is made from a single element of its constituent elements at a certain temperature. A negative value for the heat of formation indicates that it is more advantageous to exist as a compound than to exist as a single element, and a larger negative value means that the compound is more stable. Here, the heat of formation of palladium sulfide is −75.0 KJ / mol under the temperature condition of 298K, and −82.0 KJ / mol under the temperature condition of 700K. The heat of formation of palladium oxide is 245.0 KJ / mol under the temperature condition of 298K, and 241.5 KJ / mol under the temperature condition of 700K (see thermodynamic database software MALT2 (Science and Technology)). 298K is a temperature condition corresponding to room temperature, and 700K is a temperature condition corresponding to the operating temperature of the fuel cell. Thus, since palladium sulfide can be said to be more stable than palladium oxide at room temperature and fuel cell operating temperature, the bonding force between the palladium atom and the sulfur atom is the bond between the palladium atom and the oxygen atom. It can be said that it is stronger than power.

  Further, in the solid oxide constituting the electrolyte layer 21 of the present embodiment, even if a part of oxygen in the crystal structure near the interface is replaced with sulfur, sulfur is the same oxygen group element as oxygen. The nature of the oxide does not change significantly. Therefore, a decrease in proton conductivity in the solid oxide due to the introduction of sulfur can be suppressed. In the solid oxide constituting the electrolyte layer 21, introduction of sulfur is limited to a region in the vicinity of the interface even if proton conductivity is reduced to some extent by replacing some of the oxygen element with sulfur. Therefore, the battery performance can be improved by improving the durability while ensuring the proton conductivity of the electrolyte layer 21 as a whole.

In the first embodiment, in step S 110, sulfur is introduced by exposing one surface of the hydrogen permeable metal layer 22 to hydrogen sulfide (H ₂ S) gas, and palladium sulfide is formed on the surface of the hydrogen permeable metal layer 22. However, palladium sulfide may be formed by a different method. For example, the same effect can be obtained by performing a step of forming a palladium sulfide layer on one surface of the hydrogen permeable metal layer 22 by PVD instead of step S110.

C. Second embodiment:
In the first embodiment, sulfur is arranged at the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 21 by introducing sulfur element into the surface of the hydrogen permeable metal layer 22 on the side where the electrolyte layer 21 is formed. However, different configurations may be used. The structure which arrange | positions sulfur to the said interface by a different method is demonstrated below as 2nd Example. FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a single cell 120 constituting the fuel cell of the second embodiment. In FIG. 4, the same reference numerals are assigned to parts common to the fuel cell of the first embodiment shown in FIG.

  The fuel cell according to the second embodiment includes an electrolyte layer 121 adjacent to the hydrogen permeable metal layer 22 instead of the electrolyte layer 21. The electrolyte layer 121 includes a sulfide layer 125 on the hydrogen permeable metal layer 22 side and an oxide layer 126 on the cathode 24 side. Here, the sulfide layer 125 is formed of a sulfide obtained by substituting at least a part of oxygen with sulfur in the same solid oxide as the electrolyte layer 21 of the first embodiment. The oxide layer 126 is formed of the same solid oxide as the electrolyte layer 21 of the first embodiment. FIG. 5 is an explanatory view showing a manufacturing process of the MEA 140 of the second embodiment including the hydrogen permeable metal layer 22, the electrolyte layer 121, and the cathode 24.

  In order to manufacture the fuel cell of the second embodiment, first, the hydrogen permeable metal layer 22 is prepared in the same manner as in Step S100 of FIG. 2 (Step S200). Thereafter, a sulfide layer 125 is formed on one surface of the prepared hydrogen permeable metal layer 22 by, for example, PVD (step S210). Thereafter, the oxide layer 126 is formed on the sulfide layer 125 (step S220), and the cathode 24 is formed on the oxide layer 126 (step S230), thereby completing the MEA 140. Here, step S220 and step S230 are the same processes as step S120 and step S130 of FIG.

  According to the fuel cell of the second embodiment configured as described above, the sulfide layer 125 made of sulfide obtained by substituting at least part of oxygen included in the solid oxide with sulfur on the hydrogen permeable metal layer 22. And the oxide layer 126 made of a solid oxide is formed, and therefore sulfur as an oxygen group element exists at the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 121. become. Therefore, at the interface, instead of the bond between oxygen and palladium, a bond between sulfur and palladium having a stronger bond strength is formed, and the bond strength between the hydrogen permeable metal layer 22 and the electrolyte layer 121 is strengthened. Can do. In this way, by increasing the bonding force between the hydrogen permeable metal layer 22 and the electrolyte layer 121, the hydrogen permeable metal resulting from the difference in thermal expansion coefficient between the hydrogen permeable metal layer 22 and the electrolyte layer 121, etc. The damage of the layer / electrolyte composite can be suppressed, and the durability of the fuel cell can be enhanced.

  The ratio of replacing oxygen with sulfur in the sulfide layer 125 and the film thickness of the sulfide layer 125 are the effects of increasing the bonding force by replacing oxygen with sulfur, and the proton conductivity by replacing oxygen with sulfur. What is necessary is just to set suitably according to the grade of a change. The ratio of replacing oxygen with sulfur in the sulfide layer 125 can be adjusted in the film forming material used as the evaporation source, for example, when the sulfide layer 125 is formed by PVD. The film thickness of the sulfide layer 125 can be adjusted by the film formation time, for example, when the sulfide layer 125 is formed by PVD. Further, the electrolyte layer 121 is not divided into the sulfide layer 125 and the oxide layer 126, but the ratio of replacing oxygen with sulfur in the solid oxide from the hydrogen permeable metal layer 22 side to the cathode 24 side. It is good also as a structure which decreases gradually.

D. Third embodiment:
In the second embodiment, the electrolyte layer 121 is formed by sequentially forming the sulfide layer 125 and the oxide layer 126, but different configurations may be employed. A configuration in which the electrolyte layer 121 is formed by different manufacturing processes will be described below as a third embodiment. FIG. 6 is an explanatory view showing a manufacturing process of the MEA 140 in the fuel cell of the third embodiment. In the fuel cell of the third embodiment, the same reference numerals are assigned to the parts common to the first and second embodiments, and detailed description thereof is omitted.

  To manufacture the fuel cell of the third embodiment, first, the hydrogen permeable metal layer 22 is prepared in the same manner as in step S100 of FIG. 2 (step S300). Thereafter, a sulfide layer similar to the sulfide layer 125 of the second embodiment is formed on one surface of the prepared hydrogen permeable metal layer 22 by, for example, PVD (step S310). However, the sulfide layer formed in step S <b> 310 of this embodiment is thicker than the sulfide layer 125 of the second embodiment, specifically, a thickness corresponding to the entire electrolyte layer 121. Thereafter, the surface of the sulfide layer is oxidized to form an oxide layer 126 (step 320). For example, the oxidation treatment may be performed at 500 ° C. for about 1 hour in an oxidizing atmosphere. Thereby, on the surface of the sulfide layer formed in step S310, sulfur in the sulfide is replaced with oxygen, and the surface of the sulfide layer becomes an oxide layer 126 made of a solid oxide. After the oxidation treatment, the cathode 24 is formed on the oxide layer 126 in the same manner as in Step S130 (Step S330), and the MEA 140 is completed.

  According to the fuel cell of the third embodiment configured as described above, sulfur as an oxygen group element exists in the vicinity of the interface between the hydrogen permeable metal layer 22 and the electrolyte layer 121, as in the second embodiment. It will be. Therefore, at the interface, instead of the bond between oxygen and palladium, a bond between sulfur and palladium having a stronger bond strength is formed, and the bond strength between the hydrogen permeable metal layer 22 and the electrolyte layer 121 is strengthened. Can do. In this way, by increasing the bonding force between the hydrogen permeable metal layer 22 and the electrolyte layer 121, the hydrogen permeable metal resulting from the difference in thermal expansion coefficient between the hydrogen permeable metal layer 22 and the electrolyte layer 121, etc. The damage of the layer / electrolyte composite can be suppressed, and the durability of the fuel cell can be enhanced.

  In the third embodiment, the sulfide layer formed in step S310 is oxidized in step S320. However, the fuel cell can be assembled by omitting the oxidation process in step S320. In this case, by supplying an oxidizing gas to the cathode side of the assembled fuel cell and starting power generation, oxidation proceeds on the cathode side surface of the sulfide layer, and the oxide layer 126 is formed.

E. 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.

E1. Modification 1:
In the first to third embodiments, the strength of the bond between the hydrogen permeable metal layer and the electrolyte layer is improved by providing sulfur in the vicinity of the interface including the interface between the hydrogen permeable metal layer and the electrolyte layer. However, an oxygen group element other than oxygen and an element other than sulfur may be provided. That is, selenium (Se), tellurium (Te), and polonium (Po) can be used. In this case, the same effect as that obtained when sulfur is provided can be obtained.

E2. Modification 2:
In the first to third embodiments, the perovskite type solid oxide is used as the solid oxide constituting the electrolyte layer, but different types of solid oxides may be used. For example, pyrochlore type solid oxide such as La ₂ Zr ₂ O ₇ and Sm ₂ Zr _1.8 Y _0.2 O ₇ , monazite type solid oxide such as LaPO ₄ , aragonite type solid oxide such as LaBO ₃ , SiO ₂ —P ₂ Glass solid oxides such as O ₅ and SiO ₂ —H ₂ SO ₄ can be used. Even when these solid oxides are used, the bonding force between the hydrogen permeable metal layer and the electrolyte layer is provided by providing an oxygen group element other than oxygen near the interface between the hydrogen permeable metal layer and the solid oxide. A similar effect can be obtained.

E3. Modification 3:
In the first to third embodiments, the hydrogen permeable metal layer 22 is a Pd layer, but may have a different configuration. For example, the hydrogen permeable metal layer 22 can be formed of a palladium alloy such as a palladium-silver alloy. Alternatively, the hydrogen permeable metal layer 22 is formed with a palladium layer or a palladium alloy layer on both sides of a layer made of a group 5 metal having hydrogen permeability such as vanadium (V), niobium (Nb), or tantalum (Ta). It may be formed of a metal film having a three-layer structure. If the hydrogen permeable metal layer has a palladium or palladium alloy layer on at least the surface of the electrolyte layer, the same effect can be obtained by applying the present invention.

  Alternatively, the hydrogen permeable metal layer may include a noble metal other than palladium on the surface. That is, a hydrogen permeable metal layer is constituted by a metal film having a three-layer structure in which a noble metal layer having catalytic activity for dissociating and bonding hydrogen molecules is provided on both sides of a layer made of a hydrogen permeable group 5 metal. You may do it. Here, when the noble metal used has catalytic activity but the hydrogen permeation performance is not sufficient, the noble metal layer is not formed as a dense film, but the noble metal is formed in an island shape on the layer made of the group 5 metal. What is necessary is just to arrange. In general, noble metals have a weaker binding force with oxygen than base metals, but by replacing at least part of the bonds between noble metals and oxygen with bonds with noble metals and oxygen group elements other than oxygen, hydrogen permeable metal layers The same effect of increasing the strength of the bond between the electrolyte layer and the electrolyte layer can be obtained.

E4. Modification 4:
In the first to third embodiments, the hydrogen permeable metal layer is formed as a metal thin film having hydrogen permeability, that is, a self-supporting film, but may have a different configuration. For example, hydrogen permeability can be obtained by supporting a hydrogen permeable metal on a plate member having gas permeability (such as a thin plate made of stainless steel with a large number of holes, or a porous body made of metal or ceramic). A metal layer can be formed. With such a configuration, the hydrogen permeable metal layer can be further reduced in thickness.

E5. Modification 5:
In the first to third embodiments, the hydrogen permeable metal layer / electrolyte composite composed of the hydrogen permeable metal layer and the electrolyte layer is used in the solid oxide fuel cell. However, different configurations may be used. For example, the same hydrogen-permeable metal layer / electrolyte complex as in the examples can be used in devices such as a hydrogen pump and a hydrogen concentration sensor. As an example, the configuration of a hydrogen pump provided with the hydrogen permeable metal layer / electrolyte complex of the present invention will be described below.

  FIG. 7 is a schematic cross-sectional view showing a schematic configuration of a hydrogen pump 220 including the hydrogen-permeable metal layer / electrolyte layer composite of the present invention. The hydrogen pump 220 has a configuration similar to the single cell of the embodiment. In FIG. 7, the hydrogen pump 220 includes the same hydrogen permeable metal layer / electrolyte complex 23 as in the first embodiment, but includes the hydrogen permeable metal layer / electrolyte complex of other embodiments. It is also good. The hydrogen pump 220 of FIG. 7 includes an electrode 224, holders 227 and 229, and a power source 250 in addition to the hydrogen permeable metal layer / electrolyte complex 23.

  Here, the electrode 224 is formed in the same manner as the cathode 24 of the single cell 20. Further, the holders 227 and 229 have grooves having a predetermined shape on the surface thereof. In the hydrogen pump 220, the groove forms a mixed gas channel 230 or a hydrogen channel 232 between the holders 227 and 229 and the adjacent hydrogen permeable metal layer 22 or electrode 224. In the mixed gas channel 230, a mixed gas containing hydrogen supplied from the outside flows. In the hydrogen flow path 232, the hydrogen gas extracted from the mixed gas flows by the action of the hydrogen pump 220, and the hydrogen gas is discharged from the hydrogen flow path 232 to the outside of the hydrogen pump.

  The power source 250 is a DC constant voltage power source and is connected to the holders 227 and 229. The positive side of the power supply 250 is connected to the holder 229, and the negative side is connected to the holder 227. When the hydrogen pump 220 is driven, a mixed gas is supplied to the mixed gas flow path 230 while applying a voltage between both holders by the power source 250. Thereby, hydrogen in the mixed gas loses electrons in the hydrogen permeable metal layer 22 and moves as protons in the electrolyte layer 21, and the protons receive electrons again at the electrode 224 and become hydrogen gas. In this way, by using the hydrogen pump 220, high purity hydrogen is extracted from the mixed gas.

  As described above, the present invention is applied to an apparatus having an electrolyte layer having proton conductivity, and the durability of the apparatus is improved by including the hydrogen permeable metal layer / electrolyte layer composite of the present invention as the electrolyte layer. Can be made.

It is a cross-sectional schematic diagram showing the schematic structure of the single cell 20 of 1st Example. It is explanatory drawing showing the manufacturing process of MEA40. It is explanatory drawing showing the mode of the interface of a hydrogen-permeable metal layer and an electrolyte layer. It is a cross-sectional schematic diagram showing the schematic structure of the single cell 120 of 2nd Example. It is explanatory drawing showing the manufacturing process of MEA140 of 2nd Example. It is explanatory drawing showing the manufacturing process of MEA140 of 3rd Example. 2 is a schematic cross-sectional view illustrating a schematic configuration of a hydrogen pump 220. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20,120 ... Single cell 21, 121 ... Electrolyte layer 22 ... Hydrogen-permeable metal layer 23 ... Electrolyte complex 24 ... Cathode 27, 29 ... Gas separator 30 ... Single-cell fuel gas flow path 32 ... Single-cell oxidizing gas flow Road 40,140 ... MEA
125 ... sulfide layer 126 ... oxide layer 220 ... hydrogen pump 224 ... electrode 227, 229 ... holder 230 ... mixed gas flow path 232 ... hydrogen flow path 250 ... power supply

Claims (4)

A hydrogen permeable metal layer / electrolyte composite,
A hydrogen-permeable metal layer that includes a noble metal on at least one surface and selectively transmits hydrogen;
An electrolyte layer comprising a solid oxide having proton conductivity provided on the surface of the hydrogen permeable metal layer provided with the noble metal;
With
A hydrogen permeable metal layer / electrolyte complex, wherein an oxygen group element other than oxygen is disposed at least at an interface between the hydrogen permeable metal layer and the electrolyte layer. The hydrogen-permeable metal layer / electrolyte composite according to claim 1,
The oxygen group element is sulfur (S). A hydrogen permeable metal layer / electrolyte composite. The hydrogen-permeable metal layer / electrolyte composite according to claim 1 or 2,
The noble metal is palladium (Pd). A hydrogen permeable metal layer / electrolyte composite.   A fuel cell comprising the hydrogen-permeable metal layer / electrolyte complex according to any one of claims 1 to 3.

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