JP6850837B2 - Fuel cell joints and fuel cells - Google Patents

Description

The present invention relates to a fuel cell junction and a fuel cell.

Fuel cells such as alkaline fuel cells, solid oxide fuel cells, and polymer electrolyte fuel cells include an electrolyte and a pair of electrodes. This fuel cell generates electricity by supplying fuel to one electrode and an oxidizing agent to the other electrode (see, for example, Patent Document 1).

Japanese Patent No. 6496380

It is preferable to sufficiently diffuse the oxidant or fuel in the electrodes of the fuel cell. Therefore, it is an object of the present invention to improve the diffusibility of the oxidizing agent or the fuel in the electrode.

The fuel cell junction according to the first aspect of the present invention includes an electrolyte, a first electrode, a second electrode, and a plurality of first grooves. The first electrode is arranged on the first surface side of the electrolyte. The second electrode is arranged on the second surface side of the electrolyte. Each first groove extends along the first direction on the first electrode.

According to this configuration, since a plurality of first groove portions are formed on the first electrode, the oxidizing agent or fuel easily enters the first electrode through the plurality of first groove portions. As a result, the oxidant or fuel is easily diffused in the first electrode, and the diffusibility of the oxidant or fuel in the first electrode can be improved. Further, each first groove portion extends along the first direction. That is, each first groove extends along the same direction as each other. Therefore, for example, by arranging the first direction so as to intersect the supply direction of the oxidant or fuel, the diffusibility of the oxidant or fuel can be further improved.

Preferably, the fuel cell junction further comprises a plurality of second grooves. Each second groove extends along the first direction on the second electrode.

Preferably, the number of first grooves is greater than the number of second grooves.

Preferably, the first electrode is a cathode.

Preferably, the electrolyte has a porous substrate and an ionic conductor. The ionic conductor is packed in a porous substrate and has ionic conductivity.

Preferably, the electrolyte comprises a layered double hydroxide.

The fuel cell according to the second aspect of the present invention includes any of the above-mentioned fuel cell joints, a first separator, and a second separator. The first separator has a first flow path for supplying an oxidizing agent or fuel to the first electrode. The second separator has a second flow path for supplying fuel or an oxidant to the second electrode.

Preferably, in plan view, the first groove extends so as to intersect the first flow path.

According to the present invention, the diffusibility of the oxidizing agent or fuel in the electrode can be improved.

Sectional drawing of solid alkaline fuel cell. Top view of the cathode. An enlarged cross-sectional view of a fuel cell joint. FIG. 3 is a cross-sectional view of a solid alkaline fuel cell according to a modified example. FIG. 3 is a cross-sectional view of a solid alkaline fuel cell according to a modified example. Top view of the cathode according to the modified example. FIG. 3 is a cross-sectional view of a solid alkaline fuel cell according to a modified example. An enlarged cross-sectional view of a fuel cell joint according to a modified example.

Hereinafter, as an example of the fuel cell according to the present invention, an embodiment of a solid alkaline fuel cell 100, which is a kind of alkaline fuel cell (AFC) having a hydroxide ion as a carrier, will be described with reference to the drawings.

(Solid alkaline fuel cell 100)
FIG. 1 is a cross-sectional view showing the configuration of the solid alkaline fuel cell 100 according to the embodiment. The solid alkaline fuel cell 100 includes a fuel cell joint 10, a first separator 11, and a second separator 12. In the present embodiment, the solid alkaline fuel cell 100 has one fuel cell joint 10, but in actual use, the plurality of fuel cell joints 10 are the first and second. It is preferably stacked via the separators 11 and 12.

(1st and 2nd separators 11 and 12)
The first and second separators 11 and 12 are arranged so as to sandwich the fuel cell joint 10 from both sides in the thickness direction (z-axis direction). The first separator 11 is configured to supply an oxidizing agent containing _{oxygen (O 2} ) to the cathode 2 of the fuel cell junction 10 described later. The first separator 11 has a first flow path 111. The first flow path 111 faces the cathode 2. _{An oxidizing agent containing oxygen (O 2} ) is supplied to the first flow path 111.

The second separator 12 is configured to supply fuel containing a hydrogen atom (H) to the anode 3 of the fuel cell junction 10 described later. The second separator 12 has a second flow path 121. The second flow path 121 faces the anode 3 of the fuel cell junction 10 described later. Fuel containing hydrogen (H) is supplied to the second flow path 121.

When a plurality of fuel cell joints 10 are stacked via the first and second separators 11 and 12, the first separator 11 is a surface opposite to the surface on which the first flow path 111 is formed. A second flow path is formed in. Further, in the second separator 12, the first flow path is formed on the surface opposite to the surface on which the second flow path 121 is formed.

A seal member 13 is arranged between the first separator 11 and the fuel cell joint 10 and between the second separator 12 and the fuel cell joint 10. The sealing member 13 improves the adhesion between the first separator 11 and the fuel cell joint 10 and between the second separator 12 and the fuel cell joint 10, so that the oxidant or fuel can be sent to the outside. Prevent leakage. The seal member 13 has an annular shape and is in contact with the outer peripheral edge of the electrolyte 4 of the fuel cell joint 10. Examples of the seal member 13 include an O-ring and a rubber sheet. The seal member 13 may be integrally configured with the first or second separators 11 and 12.

(Fuel cell junction 10)
The fuel cell junction 10 includes a cathode 2 (an example of a first electrode), an anode 3 (an example of a second electrode), an electrolyte 4, and a plurality of first groove portions 7. The fuel cell junction 10 generates electricity at a relatively low temperature (for example, 50 ° C. to 250 ° C.) based on the following electrochemical reaction formula. However, in the following electrochemical reaction formula, methanol is used as an example of fuel.

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

(Cathode 2)
The cathode 2 is arranged on the first surface 41 side (upper surface side in FIG. 1) of the electrolyte 4. Specifically, the cathode 2 is arranged on the first surface 41 of the electrolyte 4. The cathode 2 is an anode generally called an air electrode.

FIG. 2 is a plan view of the cathode 2. As shown in FIG. 2, the cathode 2 has a rectangular shape in a plan view. The cathode 2 has a longitudinal direction (x-axis direction) and a lateral direction (y-axis direction). The anode 3 is also rectangular in a plan view, and has a longitudinal direction (x-axis direction) and a lateral direction (y-axis direction).

During power generation of the solid alkaline fuel cell 100, an oxidizing agent containing _{oxygen (O 2} ) is supplied to the cathode 2 via the first flow path 111 of the first separator 11. As the oxidizing agent, it is preferable to use air, and it is more preferable that the air is humidified. The cathode 2 is a porous body capable of diffusing an oxidizing agent inside. The porosity of the cathode 2 is not particularly limited. The thickness of the cathode 2 is not particularly limited, but can be, for example, 10 to 200 μm.

The cathode 2 is not particularly limited as long as it contains a known air electrode catalyst used for AFC. Examples of cathode catalysts include group 8-10 elements (IUPAC format periodic table) such as group 11 elements (Ru, Rh, Pd, Os, Ir, Pt) and group 11 elements (Fe, Co, Ni). Group 8-10 elements), Group 11 elements such as Cu, Ag, Au (elements belonging to Group 11 in the periodic table in the IUPAC format), rhodium phthalocyanine, tetraphenylporphyrin, Co-salene, Ni-salene ( Salen = N, N'-bis (salicylidene) ethylenediamine), silver nitrate, and any combination thereof. The amount of the catalyst supported on the cathode 2 is not particularly limited, but is preferably 0.1 to 10 mg / cm ² , more preferably 0.1 to 5 mg / cm ² . The cathode catalyst is preferably supported on carbon. Preferred examples of the cathode 2 or the catalyst constituting the cathode 2 are platinum-supported carbon (Pt / C), palladium-supported carbon (Pd / C), rhodium-supported carbon (Rh / C), nickel-supported carbon (Ni / C), and the like. Examples thereof include copper-supported carbon (Cu / C) and silver-supported carbon (Ag / C).

The method for producing the cathode 2 is not particularly limited, but for example, the cathode catalyst and, if desired, the carrier are mixed with a binder to form a paste, and the paste-like mixture is applied onto the first surface 41 of the electrolyte 4. Can be done.

(1st groove 7)
Each first groove portion 7 extends along the first direction on the cathode 2. That is, each of the first groove portions 7 extends along the same direction as each other. In the present embodiment, each of the first groove portions 7 extends along the lateral direction (y-axis direction) of the cathode 2. That is, in the present embodiment, the lateral direction of the cathode 2 corresponds to the first direction. The first groove portions 7 do not have to extend in parallel with each other. It is preferable that each first groove portion 7 has an angle of ± 15 degrees or less with respect to the adjacent first groove portion 7.

In the plan view (z-axis direction view), each first groove portion 7 extends so as to intersect the first flow path 111. Specifically, each first groove portion 7 extends along the lateral direction (y-axis direction) of the cathode 2, and the first flow path 111 extends along the longitudinal direction (x-axis direction) of the cathode 2. There is. Although not particularly limited, for example, the angle formed by the first groove portion 7 and the first flow path 111 in a plan view is preferably 90 degrees ± 10 degrees or less.

The length of each first groove portion 7 can be, for example, about 2 to 70 mm. Further, the width of each first groove portion 7 can be, for example, about 10 to 500 μm.

Each first groove portion 7 penetrates the cathode 2 in the thickness direction (z-axis direction) and reaches the electrolyte 4. That is, the electrolyte 4 is exposed through each of the first groove portions 7. It should be noted that each first groove portion 7 does not have to penetrate the cathode 2. In this case, the first groove portion 7 is formed on the cathode 2. That is, it is formed on the surface of the cathode 2 facing the first flow path 111 side.

The method for forming each of the first groove portions 7 is not particularly limited, but for example, when the cathode 2 is formed by a screen printing method, a plate making in which a pattern is formed so as to form the first groove portion 7 is used. Can be formed by Alternatively, each first groove portion 7 may be formed by laser processing or by using a groove portion forming material. The groove forming material is a material that can be removed by heat treatment or acid-alkali treatment after the cathode 2 is formed. The first groove portion 7 can be formed by removing the groove portion forming material after forming the cathode 2.

(Anode 3)
As shown in FIG. 1, the anode 3 is arranged on the second surface 42 side (lower surface side in FIG. 1) of the electrolyte 4. Specifically, the anode 3 is located on the second surface 42 of the electrolyte 4. The anode 3 is a cathode generally called a fuel electrode.

During power generation of the solid alkaline fuel cell 100, fuel containing a hydrogen atom (H) is supplied to the anode 3 via the second flow path 121 of the second separator 12. The anode 3 is a porous body capable of diffusing fuel inside. The porosity of the anode 3 is not particularly limited. The thickness of the anode 3 is not particularly limited, but can be, for example, 10 to 500 μm.

The fuel may contain a fuel compound capable of reacting with hydroxide ions (OH ⁻ ) at the anode 3, and may be in the form of either a liquid fuel or a gaseous fuel.

Examples of the fuel compound include (i) hydrazine (NH ₂ NH ₂ ), hydrated hydrazine (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 ), monomethylhydrazine (CH ₃ NHNH ₂ ), dimethylhydrazine ((CH ₃ ) ₂ NNH ₂ , CH ₃ NHNHCH ₃ ), and hydrazines such as _{carboxylic hydrazine ((NHNH 2} ) _{2 CO).} Class, (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. Examples thereof include hydroxylamines such as (v) hydroxylamine (NH ₂ OH) and hydroxylamine sulfate (NH ₂ OH · H ₂ SO ₄ ), and combinations thereof. Of these fuel compounds, carbon-free compounds (ie, hydrazine, hydrated hydrazine, hydrazine sulfate, ammonia, hydroxylamine, hydroxylamine sulfate, etc.) are particularly suitable because they do not have 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 an alcohol (for example, a lower alcohol such as methanol, ethanol, propanol or isopropanol). For example, among the above fuel compounds, hydrazine, hydrated hydrazine, monomethylhydrazine and dimethylhydrazine are liquids and can be used as they are as liquid fuels. In addition, hydrazine carbonate, hydrazine sulfate, carboxylic hydrazine, urea, imidazole, and 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 is soluble in water. As described above, the solid fuel compound can be dissolved in water or alcohol and used as a liquid fuel. When the fuel compound is dissolved in water and / or alcohol and used, the concentration of the fuel compound in the solution is, for example, 1 to 90% by weight, preferably 1 to 30% by weight.

Further, a hydrocarbon-based liquid fuel containing alcohols such as methanol and ethanol and ethers, a hydrocarbon-based gas such as methane, or pure hydrogen can be used as it is as a fuel. In particular, methanol is preferable as the fuel used in the solid alkaline fuel cell 100 according to the present embodiment. Methanol may be in a gaseous state, a liquid state, or a gas-liquid mixed state.

The anode 3 is not particularly limited as long as it contains a known anode catalyst used for AFC. Examples of anode catalysts 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. Further, a diffusion layer made of a porous material or the like may be arranged on the surface of the anode catalyst. Preferred examples of the anode 3 and the catalysts constituting the anode 3 are nickel, cobalt, silver, platinum-supported carbon (Pt / C), palladium-supported carbon (Pd / C), rhodium-supported carbon (Rh / C), and nickel-supported carbon. (Ni / C), copper-supported carbon (Cu / C), and silver-supported carbon (Ag / C) can be mentioned.

The method for producing the anode 3 is not particularly limited, but for example, the anode catalyst and, if desired, the carrier are mixed with a binder to form a paste, and the paste-like mixture is applied onto the second surface 42 of the electrolyte 4. Can be done.

(Electrolyte 4)
The electrolyte 4 is arranged between the cathode 2 and the anode 3. The electrolyte 4 is connected to each of the cathode 2 and the anode 3. The electrolyte 4 is in the form of a film and has a first surface 41 and a second surface 42. The first surface 41 and the second surface 42 face opposite to each other. The cathode 2 is arranged on the first surface 41 side of the electrolyte 4, and the anode 3 is arranged on the second surface 42 side. A sealing member 13 is arranged on the outer peripheral edge of the electrolyte 4.

FIG. 3 is a schematic view showing an enlarged cross section of the electrolyte 4. The electrolyte 4 has a porous base material 5 and an inorganic solid electrolyte body 6.

The porous base material 5 has a three-dimensional network structure. The "three-dimensional network structure" is a structure in which the constituent substances of the base material are three-dimensionally and network-likely connected. The porous base material 5 forms continuous pores 5a. The continuous pores 5a are formed by connecting the pores in a three-dimensional and mesh-like manner, and are exposed on the outer surface of the porous base material 5. The continuous pores 5a are impregnated with the inorganic solid electrolyte body 6.

The porous base material 5 can be made of a polymer material or the like. Examples of such polymer materials include polystyrene, polyether sulfone, polypropylene, epoxy resin, polyphenylene sulfide, hydrophilic fluororesin (tetrafluororesin: PTFE, etc., polyvinylidene fluoride), cellulose, nylon, and polyethylene. And any combination thereof. When the porous base material 5 is made of a flexible polymer material, the thickness can be easily reduced while increasing the porosity, so that the hydroxide ion conductivity can be improved. As the porous base material 5 made of a polymer material, a microporous membrane as commercially available as a separator for a lithium battery can be used.

The thickness of the porous substrate 5 is not particularly limited, but can be, for example, 200 μm or less, preferably 100 μm or less, more preferably 75 μm or less, still more 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 5 may be appropriately set according to the intended use, 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 5a in the cross section of the porous substrate 5 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. It is 001 to 1.0 μm, more preferably 0.001 to 0.75 μm, and particularly preferably 0.001 to 0.5 μm. Within these ranges, the density of the inorganic solid electrolyte 6 can be improved while imparting strength as a support to the porous base material 5. The average inner diameter of the continuous holes 5a is obtained by arithmetically averaging the equivalent circle diameters of the continuous holes 5a at 20 randomly selected locations on the observation image when the cross section of the porous substrate 5 is observed with an electron microscope. can get. The circle-equivalent diameter of the continuous hole 5a is the diameter of a circle having the same area as the cross-sectional area of the continuous hole 5a in the observation image. The magnification of the electron microscope may be appropriately set according to the cross-sectional size of the continuous hole 5a.

The volume fraction of the continuous hole 5a is not particularly limited, but can be, for example, 10 to 60%, preferably 15 to 55%, and more preferably 20 to 50%. Within these ranges, the density of the inorganic solid electrolyte 6 can be improved while ensuring the strength of the porous base material 5 as a support. The volume fraction of the continuous hole 5a can be measured by the Archimedes method.

Further, although not shown in FIG. 3, the porous base material 5 preferably has a plurality of pores inside itself. The plurality of pores may be connected to each other inside the porous base material 5. It is more preferable that each pore is an open pore that opens on the surface of the porous base material 5, and each pore is impregnated with the inorganic solid electrolyte body 6. As a result, a short-distance ion conduction path of continuous pores 5a → pores in the porous substrate 5 → continuous pores 5a, continuous pores 5a → pores in the porous substrate 5, → second film-like portion 63, or , The long-distance ion conduction path of the first film-like portion 62 → the pores in the porous substrate 5 → the second film-like portion 63 can be formed. As a result, the ionic conductive region in the composite portion 61 is widened, so that the ionic conductivity of the electrolyte 4 as a whole can be improved.

The inorganic solid electrolyte body 6 has hydroxide ion conductivity. During power generation of the solid alkaline fuel cell 100, the inorganic solid electrolyte 6 conducts ^{hydroxide ions (OH −) from the cathode 2 side to the anode 3 side.} The hydroxide ion conductivity of the inorganic solid electrolyte 6 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 6, the more preferable it is, and the upper limit thereof is not particularly limited, but is, for example, 10 mS / cm.

The inorganic solid electrolyte body 6 can be made of a ceramic material having hydroxide ion conductivity. As such a ceramic material, layered double hydroxide (LDH) is suitable.

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 ^The basic composition represented by the general formula of n− is an n-valent anion, n is an integer of 1 or more, x is 0.1 to 0.4, and m is an arbitrary integer meaning 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+, and} examples of ^{a n-} is _CO ^{3 2-} and OH ^- are exemplified. As M ²⁺ and M ³⁺ , one type may be used alone or two or more types may be used in combination.

LDH is composed of a plurality of hydroxide basic layers and an intermediate layer interposed between the plurality of hydroxide basic layers. Intermediate layer is composed of an anion and _{H 2} O. The hydroxide basic layer contains, for example, Ni, Al, Ti and OH groups when the metal M is Ni, Al, Ti. 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. Nickel ions in LDH are typically considered to be Ni ²⁺ , but are not particularly limited as other valences such as ^{Ni 3+ are possible.} Al in LDH can take the form of aluminum ions. Aluminum ions in LDH are typically considered to be Al ³⁺ , but are not particularly limited as other valences are possible. Ti in LDH can take the form of titanium ions. Titanium ions in LDH are typically considered to be Ti ⁴⁺ , but are not particularly limited as other valences such as ^{Ti 3+ are possible.} 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 impurity is an arbitrary element that can be unavoidably mixed in the production method, and can be mixed in LDH from, for example, a raw material or a base material.

Intermediate layer of LDH is composed of anionic and _{H 2} O. The anion is a monovalent or higher anion, preferably a monovalent or divalent ion. Preferably, the anions in LDH contain OH ⁻ and / or CO ₃ ^2- .

As described above, since the valences of Ni, Al and Ti are not always fixed, it is impractical or impossible to specify LDH strictly by a general formula. Assuming that the basic hydroxide layer is mainly composed of Ni ²⁺ , Al ³⁺ , Ti ⁴⁺ and OH groups, LDH is expressed by the general formula: Ni ²⁺ _1-xy 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 0.01 ≦ x ≦ 0.5, 0 <y <1, preferably 0.01 ≦ y ≦ 0.5, 0 <x + y <1, m is 0 or more, typically more than 0 or 1 or more It can be expressed by the basic composition (which is a real number of). 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). It should be understood as replaceable with other valence elements or ions or elements or ions that can be unavoidably mixed in the process.

The inorganic solid electrolyte body 6 has a composite portion 61 (an example of an ionic conductor), a first film-like portion 62, and a second film-like portion 63.

The composite portion 61 is arranged between the first film-like portion 62 and the second film-like portion 63. The composite portion 61 is filled in the porous base material 5. Specifically, the composite portion 61 is arranged in the continuous pores 5a of the porous base material 5. The composite portion 61 is impregnated in the continuous pores 5a of the porous base material 5 and is integrated with the porous base material 5. By supporting the inorganic solid electrolyte 6 with the porous base material 5 in this way, the strength of the inorganic solid electrolyte 6 can be improved, so that the inorganic solid electrolyte 6 can be made thinner. As a result, the resistance of the electrolyte 4 can be reduced.

In the present embodiment, the composite portion 61 extends over substantially the entire area of the continuous pores 5a of the porous base material 5. However, when the inorganic solid electrolyte body 6 does not have at least one of the first film-like portion 62 and the second film-like portion 63, the composite portion 61 may be impregnated only in a part of the porous base material 5. Good.

Here, the composite portion 61 has a plurality of closed pores 611 formed inside the composite portion 61. Since such closed pores 611 are formed inside the composite portion 61, it is possible to alleviate the volume change of the electrolyte 4 due to the change in the water content of the composite portion 61 during the operation of the solid alkaline fuel cell 100. .. As a result, it is possible to suppress the generation of stress at the interface between the electrolyte 4 and the cathode 2 and / and the interface between the electrolyte 4 and the anode 3. As a result, it is possible to prevent the electrolyte 4 from peeling off from the cathode 2 and / and the anode 3 and the electrolyte 4 itself from being deformed.

Further, since the closed pores 611 are formed inside the composite portion 61, the composite portion 61 can be provided with flexibility. Therefore, due to the temperature distribution in the solid alkaline fuel cell 100, the cathode 2 and the cathode 2 It is possible to suppress the generation of thermal stress at the interface with the electrolyte 4 and / and the interface between the anode 3 and the electrolyte 4. Therefore, it is possible to prevent the electrolyte 4 from peeling off from the cathode 2 and / and the anode 3 or the electrolyte 4 itself from being deformed.

As shown in FIG. 3, the closed pores 611 are separated from the porous substrate 5. That is, the closed air hole 611 is confined inside the composite portion 61 and does not come into direct contact with the inner surface of the continuous hole 5a. As a result, when the electrolyte 4 undergoes a volume change or deformation as compared with the case where the closed pores 611 come into direct contact with the porous base material 5, the porous base material 5, the composite portion 61, and the closed pores 611 are ternary. It is possible to prevent the composite portion 61 from peeling from the porous base material 5 starting from the corner portion made of.

The average circle-equivalent diameter of each closed hole 611 is not particularly limited, but can be, for example, 0.001 to 1.0 μm. The average circle-equivalent diameter of each closed hole 611 is preferably 0.001 μm or more, more preferably 0.002 μm or more. Thereby, the flexibility of the composite portion 61 can be further improved. The average circle-equivalent diameter of each closed hole 611 is preferably 1.0 μm or less, more preferably 0.8 μm or less. As a result, it is possible to prevent the oxidizing agent supplied to the cathode 2 from permeating to the anode 3 side or the fuel supplied to the anode 3 from permeating to the cathode 2 side.

For the average circle-equivalent diameter of each closed pore 611, the cross section of the electrolyte 4 was observed with an electron microscope at a magnification of 20,000 to 1,500,000 times, and the circle-equivalent diameter of 20 randomly selected pores 611 was calculated. Obtained by averaging. The circle-equivalent diameter of the closed pores 611 is the diameter of a circle having the same area as the closed pores 611 in the cross section of the electrolyte 4. However, since the closed pores 611 having a diameter equivalent to a circle of 0.001 μm or less have an extremely small contribution to improving the flexibility of the composite portion 61, they should be excluded when determining the average diameter equivalent to a circle of each closed hole 611. To do.

The first film-like portion 62 is connected to the cathode 2 side of the composite portion 61. The first film-like portion 62 is formed in a film-like shape. The first film-like portion 62 is formed integrally with the composite portion 61. The second film-like portion 63 is connected to the anode 3 side of the composite portion 61. The second film-like portion 63 is formed in a film-like shape. The second film-like portion 63 is integrally formed with the composite portion 61. Each of the first film-shaped portion 62 and the second film-shaped portion 63 can be made of a ceramic material having hydroxide ion conductivity. Each of the first film-like portion 62 and the second film-like portion 63 may be formed in a uniform planar shape, or may be patterned into a desired planar shape such as a striped shape. The thickness of each of the first film-like portion 62 and the second film-like portion 63 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.

(Manufacturing method of inorganic solid electrolyte body 6)
The method for producing the inorganic solid electrolyte 6 is not particularly limited, but when the inorganic solid electrolyte 6 is composed of LDH and the hydroxide basic layer of LDH contains Ni, Al, Ti and OH groups, the following It can be produced by the steps (1) to (4) of.

(1) Prepare the porous base material 5.

(2) The entire porous base material 5 is impregnated with a mixed sol of alumina and titania and heat-treated to form an alumina-titania layer. As will be described later, in order to grow LDH from the entire surface of the porous base material 5, it is important to form an alumina-titania layer on the entire surface of the porous base material 5. Therefore, a mixed sol of alumina and titania. Is impregnated and heat-treated a plurality of times. As a result, the alumina-titania layer can be formed on the entire surface of the porous base material 5.

(3) The porous base material 5 is immersed in an aqueous solution of a raw material containing ^{nickel ions (Ni 2+) and urea.}

(4) The composite portion 61, the first film-like portion 62, and the LDH are formed on the porous base material 5 and in the porous base material 5 by hydrothermally treating the porous base material 5 in the raw material aqueous solution. And an inorganic solid electrolyte body 6 having a second film-like portion 63 is formed. At this time, by appropriately adjusting the hydrothermal treatment time and the solution concentration, the closed pores 611 can be formed in the composite portion 61 by stopping the reaction before the pores are closed. Since LDH grows around the alumina-titania layer formed on the surface of the porous base material 5, when the alumina-titania layer is formed on the entire surface of the porous base material 5, the porous base material 5 is used. LDH will grow from the entire surface of the. As a result, the closed pores 611 can be separated from the porous substrate 5.

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

Modification 1
In the above embodiment, the first groove portion 7 is formed in the cathode 2, but the configuration of the fuel cell junction 10 is not limited to this. For example, as shown in FIG. 4, the first groove portion 7 may be formed in the anode 3. In this case, the anode 3 corresponds to the first electrode of the present invention.

Modification 2
As shown in FIG. 5, a plurality of first groove portions 7 may be formed on the cathode 2, and a plurality of second groove portions 8 may be formed on the anode 3. Each second groove portion 8 extends along the first direction. Specifically, each second groove portion 8 extends along the lateral direction of the anode 3. The direction in which each first groove portion 7 extends and the direction in which each second groove portion 8 extends can be substantially the same. In a plan view, each of the first groove portions 7 and each of the second groove portions 8 do not overlap each other.

The number of the first groove portions 7 can be larger than the number of the second groove portions 8. A cut surface orthogonal to the first direction is created at each of the central portion and both end portions of the first direction, and the average value of the numbers of the first and second groove portions 7 and 8 on each cut surface is the first and first. The number of 2 grooves 7 and 8 can be set.

Modification 3
In the above embodiment, each of the first groove portions 7 extends along the lateral direction of the cathode 2, but the extending direction of each first groove portion 7 is not limited to this. For example, each first groove portion 7 may extend along the longitudinal direction of the cathode 2. In this case, the longitudinal direction of the cathode 2 corresponds to the first direction of the present invention.

Modification 4
As shown in FIG. 6, each first groove portion 7 may have a different length.

Modification 5
In the above embodiment, each first groove portion 7 penetrates the cathode 2 in the thickness direction, but the configuration is not limited to this. For example, as shown in FIG. 7, each first groove portion 7 does not have to penetrate the cathode 2.

Modification 6
In the above embodiment, the closed pores 611 are separated from the porous base material 5, but as shown in FIG. 8, the closed pores 611 may be in contact with the porous base material 5. That is, the closed air hole 611 may be in direct contact with the inner surface of the continuous hole 5a. As a result, the constrained area of the porous base material 5 due to the presence of the closed pores 611 can be reduced as compared with the case where the closed pores 611 are separated from the porous base material 5, so that the flexibility of the porous base material 5 itself can be reduced. Can be improved. Therefore, when the volume of the electrolyte 4 is changed or deformed, it is possible to further suppress the generation of stress at the interface between the cathode 2 and the electrolyte 4 and / or the interface between the anode 3 and the electrolyte 4.

Modification 7
In the above embodiment, the electrolyte 4 has a plurality of closed pores 611, but if it has at least one closed pore 611, it has a composite portion as compared with the case where it does not have any closed pores 611. Since flexibility can be imparted to 61, peeling of the electrolyte 4 can be suppressed.

Modification 8
In the above embodiment, the shape of the closed hole 611 has a circular cross section, but the shape of the closed hole 611 is not limited to this. For example, the closed air hole 611 may have an elliptical cross section or may have another shape.

Modification 9
In the above embodiment, the porous base material 5 is made of a polymer material, but the material of the porous base material 5 is not limited to this. For example, the porous base material 5 can also be made of a metal material. As the metal material constituting the porous base material 5, 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 polymer material, it is possible to improve the heat dissipation efficiency of the porous base material 5 and reduce the temperature distribution in the porous base material 5. it can.

The porous base material 5 may be, for example, a cell-like or monolith-like structure made of a porous metal material (for example, a foamed metal material), or a mesh-like mass made of a fine wire metal material. It may be.

An insulating film may be formed on the surface of the porous base material 5. The insulating film can be composed of Cr ₂ O ₃ , Al ₂ O ₃ , ZrO ₂ , MgO, Mg _{Al 2} O _{4, and the} like. When the porous base material 5 is made of stainless steel, a Cr ₂ O ₃ film as an insulating film can be easily formed by oxidizing the stainless steel. Since the first and second film-like portions 62 and 63 function as an insulating film between the cathode 2 and the anode 3, even if the insulating film is not formed on the surface of the porous base material 5. Good.

Modification 10
In the above embodiment, the inorganic solid electrolyte body 6 has the composite portion 61, the first film-shaped portion 62, and the second film-shaped portion 63, but it is sufficient that the inorganic solid electrolyte body 6 has at least the composite portion 61. That is, the inorganic solid electrolyte body 6 does not have to include at least one of the first film-shaped portion 62 and the second film-shaped portion 63.

When the inorganic solid electrolyte body 6 does not include the first film-like portion 62, the composite portion 61 may be impregnated in the entire continuous pores 5a of the porous base material 5, or may be continuously impregnated with the porous base material 5. Only the region of the hole 5a on the cathode 2 side may be impregnated. When the composite portion 61 is impregnated only in the region on the cathode 2 side of the continuous pores 5a of the porous base material 5, at least a part of the anode 3 may be arranged in the void region of the continuous pores 5a. The anode 3 arranged in the void region of the continuous hole 5a may be filled in the continuous hole 5a, or may be formed in a film shape so as to cover the inner surface of the continuous hole 5a.

When the inorganic solid electrolyte body 6 does not include the second film-like portion 63, the composite portion 61 may be impregnated in the entire continuous pores 5a of the porous base material 5, or may be continuously impregnated with the porous base material 5. Only the region of the hole 5a on the anode 3 side may be impregnated. When the composite portion 61 is impregnated only in the region on the anode 3 side of the continuous pores 5a of the porous substrate 5, at least a part of the cathode 2 may be arranged in the void region of the continuous pores 5a. The cathode 2 arranged in the void region of the continuous hole 5a may be filled in the continuous hole 5a, or may be formed in a film shape so as to cover the inner surface of the continuous hole 5a.

Modification 11
In the above embodiment, the embodiment in which the fuel cell according to the present invention is applied to the polymer electrolyte fuel cell has been described, but the object to which the fuel cell according to the present invention is applied is not limited to the polymer electrolyte fuel cell, for example. It can also be applied to other fuel cells such as polymer electrolyte fuel cells.

Modification 12
In the above embodiment, the electrolyte membrane 4 is a support, but the configuration of the bonded body 10 is not limited to this. For example, the cathode 2 may be a support, or the anode 3 may be a support.

2 Cathode 3 Anode 4 Electrolyte 5 Porous base material 7 1st groove 8 2nd groove 10 Fuel cell junction 11 1st separator 12 2nd separator

Claims (9)

An electrolyte, a first electrode arranged on the first surface side of the electrolyte, a second electrode arranged on the second surface side of the electrolyte, and a plurality of electrodes extending along the first direction on the first electrode. A fuel cell junction having a first groove and a plurality of second grooves extending along the first direction on the second electrode.
A first separator having a first flow path for supplying an oxidizing agent or fuel to the first electrode,
A second separator having a second flow path for supplying fuel or an oxidant to the second electrode,
Equipped with a,
In the flat plane view, the first groove extends so as to intersect the first passage,
Each first groove is independent of each other
In a plan view, each first groove portion and each second groove portion are fuel cells that do not overlap each other.
The number of the first groove portions is larger than the number of the second groove portions.
The fuel cell according to claim 1.
The first electrode is a cathode.
The fuel cell according to claim 1 or 2.
The electrolyte is
Porous substrate and
An ionic conductor filled in the porous substrate and having ionic conductivity,
The fuel cell according to any one of claims 1 to 3.
The electrolyte comprises a layered double hydroxide.
The fuel cell according to any one of claims 1 to 4.
The first groove portion penetrates the first electrode in the thickness direction.
The fuel cell according to any one of claims 1 to 5.
The second groove portion penetrates the second electrode in the thickness direction.
The fuel cell according to any one of claims 1 to 6.
The first groove portion does not penetrate the first electrode in the thickness direction.
The fuel cell according to any one of claims 1 to 5.
In the first direction, the size of the first groove is smaller than the size of the first electrode.
The fuel cell according to any one of claims 1 to 8.

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