JP2020098781A - Solid alkaline fuel cell system and method for operating solid alkaline fuel cell - Google Patents

Abstract

To provide a solid alkaline fuel cell system capable of improving output and a method for operating the solid alkaline fuel cell.SOLUTION: A solid alkaline fuel cell system 100 includes a solid alkaline fuel cell 10, and an operating temperature control unit 11. The solid alkaline fuel cell 10 includes a cathode 12, an anode 14, and an electrolyte 16 arranged between the cathode 12 and the anode 14. The operating temperature control unit 11 has an operating temperature of 100°C or higher, and controls a desorption amount of 1/100 of the maximum desorption amount of HO when the desorption amount of HO is measured by a temperature programmed desorption method for the solid alkaline fuel cell 10 to be equal to or higher than a desorption characteristic index temperature T0 detected first.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid alkaline fuel cell system and a method for operating a solid alkaline fuel cell.

A solid alkaline fuel cell is known as a fuel cell that operates at a relatively low temperature (for example, 250° C. or lower). The alkaline fuel cell includes an anode, a cathode, and a hydroxide ion-conducting electrolyte disposed between the anode and the cathode (see, for example, Patent Document 1).

In the alkaline fuel cell, various liquid fuels or gas fuels can be used. For example, when methanol is used as a fuel, the following electrochemical reaction occurs.

Anode: CH ₃ OH+6OH ⁻ →6e ⁻ +CO ₂ +5H ₂ O
・Cathode: 3/2O ₂ +3H ₂ O+6e ⁻ →6OH ⁻
・Overall: CH ₃ OH+3/2O ₂ →CO ₂ +2H ₂ O

JP, 2016-071948, A

In such a solid alkaline fuel cell, there is a demand to improve the output by efficiently supplying H ₂ O to the cathode to improve the generation efficiency of hydroxide ions.

An object of the present invention is to provide a solid alkaline fuel cell system capable of improving output and a method of operating a solid alkaline fuel cell.

A solid alkaline fuel cell system according to the present invention includes a solid alkaline fuel cell and an operating temperature control unit. The solid alkaline fuel cell includes a cathode, an anode, and an electrolyte that is disposed between the cathode and the anode and has hydroxide ion conductivity. The operating temperature control unit controls the operating temperature of the solid alkaline fuel cell. Operating temperature control unit, the operating temperature, 100 ° C. or higher, and the first maximum amount of desorbed H _{2 O} in the case of measuring the amount of desorbed H _{2 O} by Atsushi Nobori spectroscopy for the solid alkaline fuel cell The desorption amount of /100 is controlled to be equal to or higher than the temperature at which it is initially detected.

According to the present invention, it is possible to provide a solid alkaline fuel cell system capable of improving output and a method of operating a solid alkaline fuel cell.

Sectional drawing which shows the structure of a solid alkaline fuel cell system typically. Sectional drawing which shows the structure of a solid alkaline fuel cell typically.

(Solid alkaline fuel cell system 100)
A solid alkaline fuel cell system 100 according to an embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a solid alkaline fuel cell system 100.

The solid alkaline fuel cell system 100 includes a solid alkaline fuel cell 10 and an operating temperature control unit 11.

The solid alkaline fuel cell 10 is an example of a solid alkaline fuel cell using hydroxide ions as a carrier.

As shown in FIG. 1, the solid alkaline fuel cell 10 includes a cathode 12, an anode 14, and an electrolyte 16. The cathode 12, the anode 14, and the electrolyte 16 form the “power generation unit” according to the present invention.

The solid alkaline fuel cell 10 generates power at a relatively low temperature (for example, 100° C. or higher and 250° C. or lower) based on the following electrochemical reaction formula. However, in the following electrochemical reaction formula, methanol is used as an example of fuel.

And the cathode _{12: 3 / 2O 2 + 3H} 2 O + 6e - → 6OH -
Anode 14: CH ₃ OH+6OH ⁻ →6e ⁻ +CO ₂ +5H ₂ O
・Overall: CH ₃ OH+3/2O ₂ →CO ₂ +2H ₂ O

The configuration of the solid alkaline fuel cell 10 will be described later. However, a well-known solid alkaline fuel cell can be applied to the solid alkaline fuel cell system according to the present invention.

The operating temperature control unit 11 controls the operating temperature of the solid alkaline fuel cell 10 during operation of the solid alkaline fuel cell 10. Specifically, the operating temperature control unit 11 sets the operating temperature of the solid alkaline fuel cell 10 to 100° C. or higher, and determines the desorption amount of H ₂ O for the solid alkaline fuel cell 10 by the thermal desorption method. The desorption amount of 1/100 of the maximum desorption amount of H ₂ O in the measurement is controlled to be equal to or higher than the temperature (hereinafter, referred to as “desorption characteristic index temperature T0”) that is first detected.

As described above, by controlling the operating temperature to 100° C. or higher and the desorption characteristic index temperature T0 or higher, the total amount of H ₂ O supplied to the cathode 12 can be increased and H ₂ O can be added to the cathode. It can be efficiently used for 12 electrochemical reactions. As a result, H ₂ O can be efficiently supplied to the cathode 12, so that the output of the solid alkaline fuel cell 10 can be improved. This has been confirmed experimentally.

The desorption characteristic index temperature T0 is an index indicating the ease of desorption of H ₂ O from the solid alkaline fuel cell 10. The desorption characteristic index temperature T0 is lower than the temperature at which the maximum desorption amount of H ₂ O is detected. The desorption characteristic index temperature T0 may be previously measured before the operation of the solid alkaline fuel cell 10 by a method described later.

The operating temperature of the solid alkaline fuel cell 10 is a temperature controlled for temperature control of the solid alkaline fuel cell 10. As the operating temperature, the temperature at a predetermined position in proximity to or in contact with the constantly operating solid alkaline fuel cell 10 can be used. Steadily operating means operating in a state in which the temperature change within 1 hour is within ±5 degrees. In this embodiment, the operating temperature is set to 100° C. or higher. In the present embodiment, the upper limit of the operating temperature is not particularly limited, but can be set to 250° C. or lower, for example.

The operating temperature control unit 11 controls the operating temperature of the solid alkaline fuel cell 10 by adjusting, for example, the amount of external heating by the heater, the amount of internal heating by the amount of power generation, the cooling amount by air cooling, water cooling, or the like. be able to. In FIG. 1, the operating temperature control unit 11 is configured to measure the temperature at a position close to the cathode 12, but it is possible to measure the temperature at a predetermined position close to or in contact with the solid alkaline fuel cell 10. It only has to be configured.

Here, the desorption characteristic index temperature T0 is detected by a thermal desorption method using H ₂ O (so-called H ₂ O-TPD) as described below.

(1) A part of the power generation part of the solid alkaline fuel cell 10 is cut out to form a test piece, and the test piece is held in a sample holder of a TPD device (AutoChemII 2920 manufactured by Micromeritics).

(2) The test piece is heated to 250° C. in Ar gas and held for 3 hours.

(3) Cool the test piece to room temperature (50° C. or lower).

(4) Water humidified Ar gas is supplied to the test piece at room temperature to physically adsorb H ₂ O on the test piece.

(5) Purge the test piece in dry Ar gas for 30 minutes.

(6) The test piece is heated from room temperature to 250° C. at a heating rate of 10° C./min.

(7) The maximum desorption amount (peak value) of H ₂ O is specified in the desorption curve showing the change over time of the desorption amount of H ₂ O detected by the gas detector. At this time, if two peaks overlap each other in the desorption curve, the two peaks are separated by multivariate analysis, and the peak value on the low temperature side is adopted as the maximum desorption amount. The desorption amount of H ₂ O is not particularly limited, but is preferably 0.1 μmol-H ₂ O/m ² or more, more preferably 1 μmol-H ₂ O/m ² or more. Desorption of the _{H 2 O (μmol-H 2} O / m 2) is to normalizing of _{H 2} O desorption amount at _H 2 O-TPD against a BET specific surface area ^(m 2 / g) It is calculated by. The total amount of desorbed H ₂ O can be measured by a quadrupole mass spectrometer (Quadrupole Mass Spectrometer: QMS, ThermoStar GSD320 manufactured by Pfeiffer Vacuum).

(8) In the desorption curve, the temperature at which the desorption amount of 1/100 of the maximum desorption amount of H ₂ O is first shown (that is, the desorption amount of H ₂ O gradually increases toward the maximum desorption amount). On the increasing curve, the temperature indicating the desorption amount of 1/100 of the maximum desorption amount of H ₂ O) is specified as the desorption characteristic index temperature T0. The desorption amount of 1/100 of the maximum desorption amount of H ₂ O is not particularly limited, but the H ₂ O amount desorbed by the desorption characteristic index temperature T0 is 0.3 μmol-H ₂ O/m ² or more. It is preferably 0.8 μmol-H ₂ O/m ² or more.

Regarding the method for detecting the desorption characteristic index temperature by the thermal desorption method, see Sumika Chemical Analysis Service Technical News TN136 “Acid/basic measurement of solid catalyst (thermal desorption method (TPD))”, [2018 Search on November 22, 2014], and the details are described on the Internet <URL: https://www.scas.co.jp/technical-informations/technical-news/pdf/tn136.pdf>.

Further, the operating temperature control unit 11 sets the operating temperature of the solid alkaline fuel cell 10 to 100° C. or higher during operation of the solid alkaline fuel cell 10 and 1/10 of the maximum desorption amount of H ₂ O described above. It is preferable to control the desorption amount of the above to be equal to or higher than the temperature at which it is first detected (hereinafter, referred to as “desorption characteristic index temperature T1”).

As described above, by controlling the operating temperature to 100° C. or higher and the desorption characteristic index temperature T1 or higher, the total amount of H ₂ O supplied to the cathode 12 can be further increased and H ₂ O It can be used more efficiently for the electrochemical reaction of the cathode 12. As a result, H ₂ O can be supplied to the cathode 12 more efficiently, so that the output of the solid alkaline fuel cell 10 can be further improved. This has also been confirmed experimentally.

The desorption characteristic index temperature T1 is an index indicating the ease of desorption of H ₂ O from the solid alkaline fuel cell 10, like the desorption characteristic index temperature T0 described above. The desorption characteristic index temperature T1 is higher than the desorption characteristic index temperature T0 and lower than the temperature at which the maximum desorption amount of H ₂ O is detected.

The desorption characteristic index temperature T1 of the solid alkaline fuel cell 10 is a temperature at which a desorption amount of 1/10 of the maximum desorption amount of H ₂ O is first shown in the detection method of the desorption characteristic index temperature T0 described above. Is detected by specifying The desorption characteristic index temperature T1 may be measured in advance before the operation of the solid alkaline fuel cell 10.

(Structure of solid alkaline fuel cell 10)
As shown in FIG. 1, the solid alkaline fuel cell 10 includes a cathode 12, an anode 14, and an electrolyte 16.

(Cathode 12)
The cathode 12 is connected to the electrolyte 16. The cathode 12 is an anode generally called an air electrode. During the power generation of the solid alkaline fuel cell 10, the oxidant containing oxygen (O ₂ ) is supplied to the cathode 12 via the oxidant supply means 13. Air is preferably used as the oxidant, and the air is more preferably humidified. The cathode 12 is a porous body capable of diffusing an oxidant inside. The porosity of the cathode 12 is not particularly limited. The thickness of the cathode 12 is not particularly limited, but may be 10 to 200 μm, for example.

The cathode 12 is not particularly limited as long as it contains a known cathode catalyst used for AFC. Examples of the cathode catalyst include platinum group elements (Ru, Rh, Pd, Ir, Pt), iron group elements (Fe, Co, Ni), and other group 8-10 elements (8th group in the IUPAC format). Group 10 elements), Group 11 elements such as Cu, Ag, Au (elements belonging to Group 11 in the IUPAC format of the periodic table), rhodium phthalocyanine, tetraphenylporphyrin, Co salen, Ni salen (salen= N,N′-bis(salicylidene)ethylenediamine), silver nitrate, and any combination thereof.

The cathode catalyst may be supported on a carrier. Carbon particles are preferred as the carrier. Preferable examples of the constituent material of the cathode 12 include platinum-supporting carbon (Pt/C), platinum-cobalt-supporting carbon (PtCo/C), palladium-supporting carbon (Pd/C), rhodium-supporting carbon (Rh/C), nickel-support. Examples thereof include carbon (Ni/C), copper-supported carbon (Cu/C), and silver-supported carbon (Ag/C). The amount of catalyst supported on the cathode 12 is not particularly limited, but is preferably 0.05 to 10 mg/cm ² , and more preferably 0.05 to 5 mg/cm ² .

The method for producing the cathode 12 is not particularly limited. For example, the cathode 12 may be formed by mixing the cathode catalyst and, if desired, a carrier with a binder to form a paste, and applying this paste mixture to the cathode side surface 16S of the electrolyte 16. it can.

(Anode 14)
The anode 14 is connected to the electrolyte 16. The anode 14 is a cathode generally called a fuel electrode. During the power generation of the solid alkaline fuel cell 10, the fuel containing hydrogen atoms (H) is supplied to the anode 14 via the fuel supply means 15. The anode 14 is a porous body capable of diffusing fuel inside. The porosity of the anode 14 is not particularly limited. The thickness of the anode 14 is not particularly limited, but may be 10 to 500 μm, for example.

The hydrogen atom-containing fuel only needs to contain a fuel compound capable of reacting with hydroxide ions (OH ⁻ ) in the anode 14, and may be in the form of either a liquid fuel or a gas fuel.

Examples of the fuel compound include (i) hydrazine (NH ₂ NH ₂ ), hydrazine hydrate (NH ₂ NH ₂ ·H ₂ O), hydrazine carbonate ((NH ₂ NH ₂ ) ₂ CO ₂ ), and hydrazine sulfate (NH). ₂ NH ₂ ·H ₂ SO ₄ ), hydrazine such as monomethylhydrazine (CH ₃ NHNH ₂ ), dimethylhydrazine ((CH ₃ ) ₂ NNH ₂ , CH ₃ NHNHCH ₃ ), and carvone hydrazide ((NHNH ₂ ) ₂ CO). , (Ii) Urea (NH ₂ CONH ₂ ), (iii) Ammonia (NH ₃ ), (iv) Imidazole, 1,3,5-triazine, 3-amino-1,2,4-triazole and other heterocycles Compounds, (v) hydroxylamines (NH ₂ OH), hydroxylamine sulfates (NH ₂ OH.H ₂ SO ₄ ), and other hydroxylamines, and combinations thereof. Of these fuel compounds, carbon-free compounds (that is, hydrazine, hydrazine hydrate, hydrazine sulfate, ammonia, hydroxylamine, hydroxylamine sulfate, and the like) are particularly preferable because they do not cause the problem of catalyst poisoning by carbon monoxide. is there.

The fuel compound may be used as a fuel as it is, or may be used as a solution dissolved in water and/or alcohol (for example, lower alcohol such as methanol, ethanol, propanol, isopropanol, etc.). For example, among the above fuel compounds, hydrazine, hydrated hydrazine, monomethylhydrazine and dimethylhydrazine are liquids, and thus can be used as they are as liquid fuels. Further, hydrazine carbonate, hydrazine sulfate, carboxylic hydrazide, urea, imidazole, 3-amino-1,2,4-triazole, and hydroxylamine sulfate are solid but soluble in water. 1,3,5-Triazine and hydroxylamine are solid but soluble in alcohol. Ammonia is a gas but soluble in water. Thus, the solid fuel compound can be dissolved in water or alcohol and used as a liquid fuel. When the fuel compound is used by dissolving it in water and/or alcohol, the concentration of the fuel compound in the solution is, for example, 30 to 99.9% by weight, preferably 66 to 99.9% by weight.

Further, hydrocarbon-based liquid fuel containing alcohols such as methanol and ethanol or ethers, hydrocarbon-based gas such as methane, or pure hydrogen can be directly used as fuel. In particular, methanol is suitable as the fuel used in the solid alkaline fuel cell 10 according to the present embodiment. Methanol may be in a gas state, a liquid state, or a gas-liquid mixed state.

The anode 14 is not particularly limited as long as it includes a known anode catalyst used for AFC. Examples of the anode catalyst include metal catalysts such as Pt, Ni, Co, Fe, Ru, Sn, and Pd. The metal catalyst is preferably supported on a carrier such as carbon, but may be in the form of an organic metal complex having a metal atom of the metal catalyst as a central metal, or the organic metal complex may be supported as a carrier. Preferred examples of the anode 14 and the catalyst constituting the anode 14 are nickel, cobalt, silver, platinum-supporting carbon (Pt/C), platinum-ruthenium-supporting carbon (PtRu/C), palladium-supporting carbon (Pd/C), and rhodium-support. Examples thereof include carbon (Rh/C), nickel-supporting carbon (Ni/C), copper-supporting carbon (Cu/C), and silver-supporting carbon (Ag/C).

The method for producing the anode 14 is not particularly limited. For example, the anode 14 may be formed by mixing the anode catalyst and, if desired, a carrier with a binder to form a paste, and applying the paste mixture to the anode-side surface 16T of the electrolyte 16. it can.

(Electrolyte 16)
The electrolyte 16 is disposed between the cathode 12 and the anode 14. The electrolyte 16 is connected to each of the cathode 12 and the anode 14. The electrolyte 16 has a cathode-side surface 16S that contacts the cathode 12 and an anode-side surface 16T that contacts the anode 14. The electrolyte 16 is formed in a film shape, a layer shape, or a sheet shape.

FIG. 2 is a schematic view showing an enlarged cross section of the electrolyte 16. The electrolyte 16 has a porous base material 20 and an inorganic solid electrolyte body 22.

The porous substrate 20 has a three-dimensional network structure. The “three-dimensional mesh structure” is a structure in which the constituent materials of the base material are three-dimensionally and meshed. The porous substrate 20 forms continuous holes 20a. The continuous holes 20 a are formed by connecting the holes in a three-dimensional and mesh shape, and are exposed on the outer surface of the porous substrate 20. The continuous hole 20a is impregnated with an inorganic solid electrolyte body 22 described later.

The porous substrate 20 can be made of at least one selected from metal materials, ceramic materials, and polymer materials.

As the metal material forming the porous substrate 20, stainless steel (Fe-Cr alloy, Fe-Ni-Cr alloy, etc.), aluminum, zinc, nickel, titanium, or the like can be used. Since such a metal material has higher thermal conductivity than a ceramic material or a polymer material, it is possible to improve the heat dissipation efficiency of the porous base material 20 and reduce the temperature distribution in the porous base material 20. Can be made. The form of the porous substrate 20 is not particularly limited as long as it has a three-dimensional network structure, and may be, for example, a cell-like or monolith-like structure made of a porous metal material (for example, a foam metal material). It may be a mesh-shaped mass made of a thin wire metal material.

When the porous substrate 20 is made of a metal material, an insulating film may be formed on the surface of the porous substrate 20. The insulating film can be made of Cr ₂ O ₃ , Al ₂ O ₃ , ZrO ₂ , MgO, MgAl ₂ O _4, or the like. When the porous substrate 20 is made of stainless steel, the Cr ₂ O ₃ film as an insulating film can be easily formed by oxidizing the stainless steel. However, in the present embodiment, the first and second film-shaped portions 22b and 22c, which will be described later, function as insulating films between the cathode 12 and the anode 14, respectively. The film may not be formed.

Examples of the ceramic material forming the porous substrate 20 include alumina, zirconia, titania, magnesia, calcia, cordierite, zeolite, mullite, zinc oxide, silicon carbide, and any combination thereof.

As the polymer material forming the porous substrate 20, polystyrene, polyether sulfone, polypropylene, epoxy resin, polyphenylene sulfide, fluororesin (tetrafluorinated resin: PTFE, etc.), cellulose, nylon, polyethylene, polyimide and the like. Any combination of When the porous base material 20 is made of a flexible polymer material, since it is easy to reduce the thickness of the continuous pores 20a while increasing the volume thereof, the hydroxide ion conductivity can be improved. A commercially available microporous membrane can be used as the porous substrate 20 made of a polymer material.

The thickness of the porous substrate 20 is not particularly limited, but can be, for example, 200 μm or less, preferably 100 μm or less, more preferably 75 μm or less, further preferably 50 μm or less, particularly preferably 25 μm or less, and 5 μm. The following are the most preferable. The lower limit of the thickness of the porous base material 20 may be appropriately set according to the application, but is preferably 1 μm or more, more preferably 2 μm or more in order to secure a certain degree of hardness.

The average inner diameter of the continuous holes 20a in the cross section of the porous substrate 20 is not particularly limited, but can be, for example, 0.001 to 1.5 μm, preferably 0.001 to 1.25 μm, and more preferably 0. 001 to 1.0 μm, more preferably 0.001 to 0.75 μm, and particularly preferably 0.001 to 0.5 μm. By setting it as these ranges, the density of the inorganic solid electrolyte body 22 can be improved, giving the strength as a support body to the porous base material 20. The average inner diameter of the continuous holes 20a is obtained by arithmetically averaging the circle-equivalent diameters of the 20 continuous holes 20a randomly selected on the observed image when the cross section of the porous substrate 20 is observed with an electron microscope. can get. The equivalent circle diameter of the continuous hole 20a is the diameter of a circle having the same area as the cross-sectional area of the continuous hole 20a in the observed image. The magnification of the electron microscope may be set appropriately according to the cross-sectional size of the continuous hole 20a.

The volume ratio of the continuous holes 20a is not particularly limited, but may be, for example, 10 to 60%, preferably 15 to 55%, more preferably 20 to 50%. By setting it as these ranges, the density of the inorganic solid electrolyte body 22 can be improved, ensuring the strength as a support body in the porous base material 20. The volume ratio of the continuous holes 20a can be measured by the Archimedes method.

Although not shown in FIG. 2, the porous substrate 20 preferably has a plurality of pores inside itself. The plurality of pores may be connected to each other inside the porous substrate 20. It is more preferable that each pore is an open pore that opens on the surface of the porous base material 20, and that each pore is impregnated with the inorganic solid electrolyte body 22. As a result, a short-distance ion conduction path of continuous pore 20a→pore in porous substrate 20→continuous pore 20a, continuous pore 20a→pore in porous substrate 20→second membrane portion 22c, or It is possible to form a long-distance ion conduction path of the first membrane portion 22b→the pores in the porous substrate 20→the second membrane portion 22c. As a result, the ion-conductive region in the composite portion 22a is expanded, so that the ion conductivity of the electrolyte 16 as a whole can be improved.

The inorganic solid electrolyte body 22 has hydroxide ion conductivity. During power generation of the solid alkaline fuel cell 10, the inorganic solid electrolyte body 22 conducts hydroxide ions (OH ⁻ ) from the cathode 12 side to the anode 14 side. The hydroxide ion conductivity of the inorganic solid electrolyte body 22 is not particularly limited, but is preferably 0.1 mS/cm or more, more preferably 0.5 mS/cm or more, and further preferably 1.0 mS/cm or more. The higher the hydroxide ion conductivity of the inorganic solid electrolyte body 22, the more preferable, and the upper limit value thereof is not particularly limited, but is, for example, 10 mS/cm.

The inorganic solid electrolyte body 22 is preferably dense. The relative density of the inorganic solid electrolyte body 22 calculated by the Archimedes method is not particularly limited, but is preferably 90% or more, more preferably 92% or more, further preferably 95% or more. The inorganic solid electrolyte body 22 can be densified by, for example, hydrothermal treatment.

The inorganic solid electrolyte body 22 can be made of a ceramic material having hydroxide ion conductivity. As such a ceramic material, a well-known ceramic having hydroxide ion conductivity can be used, but a layered double hydroxide (LDH: Layered Double Hydroxide) described below is particularly preferable.

LDH is M ²⁺ _1−x M ³⁺ _x (OH) ₂ A ⁿ⁻ x/n·mH ₂ O (in the formula, M ²⁺ is a divalent cation, M ³⁺ is a trivalent cation, and A ^n- is an anion of valence, n is an integer of 1 or more, x is 0.1 to 0.4, and m is an arbitrary integer which means the number of moles of water). Have. Examples of M ²⁺ include Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , and Zn ²⁺ , and examples of M ³⁺ include Al ³⁺ , Fe ³⁺ , Ti ³⁺ , ^{Y 3+, Ce 3+, Mo 3+} , and ^{Cr 3+} can be mentioned, An ^- and the like ^- _CO ^{3 2-and} OH examples of. As M ²⁺ and M ³⁺ , one type may be used alone, or two or more types may be used in combination.

The LDH is composed of a plurality of hydroxide basic layers and an intermediate layer interposed between the plurality of hydroxide basic layers. The intermediate layer is composed of anions and H ₂ O. The hydroxide basic layer contains Ni, Al, Ti and OH groups when the metal M is Ni, Al or Ti, for example. Hereinafter, a case where the hydroxide basic layer of LDH contains Ni, Al, Ti and OH groups will be described.

Ni in LDH can take the form of nickel ions. The nickel ion in LDH is considered to be typically Ni ²⁺ , but is not particularly limited because it may have other valences such as Ni ³⁺ . Al in LDH can take the form of aluminum ions. The aluminum ion in LDH is considered to be typically Al ³⁺ , but is not particularly limited because it may have other valences. Ti in LDH can take the form of titanium ions. The titanium ion in LDH is considered to be typically Ti ⁴⁺ , but it is not particularly limited because it may have other valences such as Ti ³⁺ . The hydroxide basic layer preferably contains Ni, Al, Ti and OH groups as main constituent elements, but may contain other elements or ions, or may contain unavoidable impurities. The unavoidable impurities are arbitrary elements that can be inevitably mixed in the manufacturing method, and can be mixed in LDH, for example, originating from the raw material or the base material.

The intermediate layer of LDH is composed of anions and H ₂ O. The anion is a monovalent or higher valent anion, preferably a monovalent or divalent ion. Preferably, the anions in LDH include OH ⁻ and/or CO ₃ ²⁻ .

As described above, since the valences of Ni, Al and Ti are not always clear, it is impractical or impossible to specify LDH exactly by using a general formula. If it is assumed that the hydroxide basic layer is mainly composed of Ni ²⁺ , Al ³⁺ , Ti ⁴⁺ and OH groups, LDH has the general formula: Ni ²⁺ _1−x−y Al ³⁺ _x Ti ⁴⁺ _y (OH _{^{) 2 a n- (x + 2y}} ) / n · mH 2 O ( ^{wherein, a n-n-valent} anion, n is an integer of 1 or more, preferably 1 or 2, 0 <x <1, preferably Is 0.01≦x≦0.5, 0<y<1, preferably 0.01≦y≦0.5, 0<x+y<1, and m is 0 or more, typically more than 0 or 1 or more. Is a real number). However, the above general formula should be understood as “basic composition” to the extent that elements such as Ni ²⁺ , Al ³⁺ and Ti ⁴⁺ do not impair the basic characteristics of LDH and other elements or ions (of the same element). (Including elements or ions having other valences or elements or ions which may be unavoidably mixed in the manufacturing process).

In the present embodiment, the inorganic solid electrolyte body 22 has a composite part 22a, a first film-shaped part 22b, and a second film-shaped part 22c.

The composite part 22a is arranged between the first film-shaped part 22b and the second film-shaped part 22c. The composite part 22a is arranged in the continuous hole 20a of the porous substrate 20. The composite portion 22a is impregnated in the continuous hole 20a and is integrated with the porous substrate 20. Since the strength of the inorganic solid electrolyte body 22 can be improved by supporting the inorganic solid electrolyte body 22 with the porous base material 20 in this manner, the inorganic solid electrolyte body 22 can be thinned. As a result, the resistance of the electrolyte 16 can be reduced.

In the present embodiment, the composite portion 22a is spread over substantially the entire area of the continuous pores 20a of the porous base material 20, but the inorganic solid electrolyte body 22 has at least the first membrane portion 22b and the second membrane portion 22c. When not having one, the composite part 22a may be impregnated only in a part of the porous substrate 20.

The first film-shaped portion 22b is continuous with the cathode 12 side of the composite portion 22a. The first film-shaped portion 22b is formed in a film shape. The first film-shaped portion 22b is formed integrally with the composite portion 22a. The second film-shaped portion 22c is continuous with the anode 14 side of the composite portion 22a. The second film-shaped portion 22c is formed in a film shape. The second film-shaped portion 22c is integrally formed with the composite portion 22a. Each of the first film-shaped portion 22b and the second film-shaped portion 22c is composed of a hydroxide ion conductive ceramics component. The thickness of each of the first film-shaped portion 22b and the second film-shaped portion 22c is not particularly limited, but can be, for example, 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less. Each of the first film-shaped portion 22b and the second film-shaped portion 22c may be formed in a uniform planar shape, or may be patterned into a desired planar shape such as a stripe shape.

The method for producing the electrolyte 16 is not particularly limited, but for example, the following method can be adopted. First, a mixed sol of alumina and titania is prepared, and this mixed sol is permeated into the whole or most of the inside of the porous substrate 20. Next, the porous base material 20 in which the mixed sol has permeated is heat-treated (atmosphere atmosphere, 50 to 150 degrees, 1 to 30 minutes) to form an alumina/titania layer in each hole of the porous base material 20. .. Next, the porous base material 20 is immersed in a raw material aqueous solution containing nickel ions (Ni2+) and urea. Next, the porous substrate 20 is hydrothermally treated in the raw material aqueous solution. At this time, by appropriately adjusting the hydrothermal treatment conditions (100 to 150 degrees, 10 to 100 hours), the composite portion 22a is formed in the porous base material 20 and both main surfaces of the porous base material 20 are formed. The first film-shaped portion 22b and the second film-shaped portion 22c are formed to serve as the electrolyte 16.

(Modification of the embodiment)
Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made without departing from the spirit of the present invention.

In the above embodiment, the electrolyte 16 has the configuration shown in FIG. 2, but the configuration is not limited to this. For example, although the electrolyte 16 has the porous base material 20 that supports the inorganic solid electrolyte body 22, the electrolyte 16 may not have the porous base material 20. In this case, the electrolyte 16 can be composed of a plate-shaped inorganic solid electrolyte body. The electrolyte 16 may not have at least one of the first film-shaped portion 22b and the second film-shaped portion 22c.

Further, the electrolyte 16 may be formed by forming an inorganic solid electrolyte body 22 having hydroxide ion conductivity into a film shape. Further, the electrolyte 16 may be formed by compacting a mixed powder of the hydroxide ion conductive material powder and the binder material powder.

10 Solid Alkaline Fuel Cell 11 Operating Temperature Control Part 12 Cathode 14 Anode 16 Electrolyte 16S Cathode Side Surface 16T Anode Side Surface 20 Porous Base Material 22 Inorganic Solid Electrolyte Body 22a Composite Part 22b First Membrane Part 22c Second Membrane Part

Claims (2)

A solid alkaline fuel cell comprising a cathode, an anode, and an electrolyte having hydroxide ion conductivity, the electrolyte being disposed between the cathode and the anode;
An operating temperature control unit for controlling the operating temperature of the solid alkaline fuel cell;
Equipped with
The operating temperature control unit, the operating temperature, 100 ° C. or higher, and the maximum desorption of H _{2 O} in the case of measuring the amount of desorbed H _{2 O} by Atsushi Nobori spectroscopy for the solid alkaline fuel cell The desorption amount of 1/100 of the amount is controlled to be equal to or higher than the temperature at which it is initially detected,
Solid alkaline fuel cell system. A method of operating a solid alkaline fuel cell, comprising: a cathode, an anode, and an electrolyte having hydroxide ion conductivity, the electrolyte being disposed between the cathode and the anode,
The operating temperature of the solid alkaline fuel cell, 100 ° C. or higher, and the maximum amount of released H _{2 O} in the case of measuring the amount of desorbed H _{2 O} by Atsushi Nobori spectroscopy for the solid alkaline fuel cell The desorption amount of 1/100 of the
Operating method of solid alkaline fuel cell.

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