JP6924229B2 - Electrochemical cell - Google Patents

Description

The present invention relates to an electrochemical cell.

The electrochemical cell used for an alkaline fuel cell (AFC), a polymer electrolyte fuel cell (PEFC), or the like has a conjugate for an electrochemical cell. This conjugate has an electrolyte membrane, a cathode, and an anode. The electrochemical cell generates electricity by supplying fuel to the anode and an oxidizing agent such as air to the cathode.

The electrochemical cell further has a frame-shaped member. The frame-shaped members are arranged so as to surround the joint, and the fuel gas, the oxidant gas, and the like are supplied to the joint via the frame-shaped members and the like (for example, Patent Document 1).

JP-A-2019-50112

In the electrochemical cell as described above, since the bonded body is restrained by the frame-shaped member, thermal stress is generated by thermal expansion or contraction, which may cause various problems. Therefore, an object of the present invention is to relieve the thermal stress that may occur in the metallurgical cell junction.

The electrochemical cell according to a certain aspect of the present invention includes a frame-shaped member and a joining body for an electrochemical cell. The frame-shaped member has an opening. The electrochemical cell joint is arranged in the opening of the frame-shaped member. The joint for an electrochemical cell is held by a frame-shaped member. The electrochemical cell joint has at least one bent portion that is bent in a ridge shape at the outer peripheral edge portion.

According to this configuration, since the electrochemical cell joint has a bent portion at the outer peripheral edge portion, when a thermal stress is generated in the electrochemical cell joint, the thermal stress is relaxed by the bent portion. be able to.

Preferably, the electrochemical cell conjugate has an electrolyte membrane and a first electrode. The electrolyte membrane is held by the frame-shaped member. The first electrode is arranged in a region excluding the outer peripheral edge portion on one surface of the electrolyte membrane. The bent portion is arranged on the outer peripheral edge portion of the electrolyte membrane.

According to this configuration, since the electrolyte membrane is held by the frame-shaped member, thermal stress can be generated in the electrolyte membrane of the electrochemical cell joint. Here, since the electrolyte membrane has a bent portion at the outer peripheral edge portion thereof, when a thermal stress is generated in the electrolyte membrane, the thermal stress can be relaxed by the bent portion.

Preferably, the electrochemical cell junction has a second electrode. The second electrode is arranged in a region excluding the outer peripheral edge portion on the other surface of the electrolyte membrane.

Preferably, the electrochemical cell conjugate has a first electrode and an electrolyte membrane. The first electrode is held by the frame-shaped member. The electrolyte membrane is arranged in a region excluding the outer peripheral edge portion on one surface of the first electrode. The bent portion is arranged on the outer peripheral edge portion of the first electrode.

According to this configuration, since the first electrode is held by the frame-shaped member, thermal stress can be generated in the first electrode of the electrochemical cell joint. Here, since the first electrode has a bent portion at the outer peripheral edge portion thereof, when a thermal stress is generated in the first electrode, the thermal stress can be relaxed by the bent portion.

Preferably, the electrochemical cell conjugate has a second electrode that is located on the electrolyte membrane.

Preferably, the electrochemical cell junction has a first electrode, an electrolyte membrane, and a second electrode. The electrolyte membrane is placed all over one surface of the first electrode. The second electrode is arranged in a region excluding the outer peripheral edge portion on one surface of the electrolyte membrane. The frame-shaped member holds the first electrode and the electrolyte membrane. The bent portion is arranged on the first electrode and the outer peripheral edge portion of the electrolyte membrane.

According to this configuration, since the first electrode and the electrolyte membrane are held by the frame-shaped member, thermal stress can be generated in the first electrode and the electrolyte membrane in the electrochemical cell junction. Here, since the bent portion is arranged on the outer peripheral edge portion of the first electrode and the electrolyte membrane, when thermal stress is generated in the first electrode and the electrolyte membrane, the thermal stress can be relaxed by the bent portion.

Preferably, the metallurgical cell junction is rectangular in plan view. The bends are located at the corners of the electrochemical cell junction.

Preferably, the bend extends along the direction in which the outer peripheral edge of the electrochemical cell junction extends.

Preferably, the bent portion extends annularly along the direction in which the outer peripheral edge of the electrochemical cell junction extends.

Preferably, the bent portion extends toward the frame-like member at the outer peripheral edge of the electrochemical cell joint.

Preferably, the bend extends continuously.

Preferably, the bend extends intermittently.

Preferably, the bends include a plurality of bends that extend in multiple rows.

Preferably, the bent portion extends so as to be in contact with the first electrode.

Preferably, the bend extends in contact with the electrolyte membrane.

Preferably, the bent portion extends so as to be in contact with the second electrode.

Preferably, the electrolyte membrane has a porous substrate and an ionic conductor. The porous substrate has a three-dimensional network structure. The porous substrate forms continuous pores. The ionic conductor has ionic conductivity. The ionic conductor is arranged in the continuous pores.

Preferably, the electrolyte membrane has a first membranous portion and a second membranous portion. The first film-like portion covers the first main surface of the porous base material. The second membranous portion covers the second main surface of the porous substrate.

Preferably, the ionic conductor has closed pores inside.

Preferably, the closed pores are separated from the porous substrate.

Preferably, the closed pores are in contact with the porous substrate.

Preferably, the ionic conductor has a plurality of closed pores.

Preferably, the porous substrate has pores inside. The pores are impregnated with an ionic conductor.

According to the present invention, the thermal stress that may occur in the electrolyte membrane can be relaxed.

Sectional view of the fuel cell. Top view of the fuel cell. Enlarged sectional view of the fuel cell. Enlarged sectional view of the fuel cell. The plan view of the fuel cell which concerns on the modification. The plan view of the fuel cell which concerns on the modification. The plan view of the fuel cell which concerns on the modification. The plan view of the fuel cell which concerns on the modification. An enlarged cross-sectional view of a fuel cell according to a modified example. The plan view of the fuel cell which concerns on the modification. The plan view of the fuel cell which concerns on the modification. An enlarged cross-sectional view of a fuel cell according to a modified example. Sectional drawing of the fuel cell which concerns on modification. Sectional drawing of the fuel cell which concerns on modification.

Hereinafter, an embodiment of a solid alkaline fuel cell 100 (an example of an electrochemical cell), which is a type of alkaline fuel cell (AFC) using hydroxide ions 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 (hereinafter, simply referred to as “fuel cell 100”) includes a frame-shaped member 7, an electrochemical cell joint 10 (hereinafter, simply referred to as “joint 10”), and a plurality of separators. 11 and a plurality of sealing portions 12. In actual use, it is preferable that a plurality of fuel cells 100 are stacked.

(Separator 11)
The separator 11 is arranged so as to sandwich the bonded body 10 from both sides in the thickness direction (z-axis direction). The separator 11 has a gas flow path 111. The gas flow path 111 faces the cathode 2 or the anode 3 of the bonded body 10 described later.

_{An oxidizing agent containing oxygen (O 2} ) is supplied to the gas flow path 111 facing the cathode 2. Fuel containing a hydrogen atom (H) is supplied to the gas flow path 111 facing the anode 3.

(Seal part 12)
The seal portion 12 is arranged between the separator 11 and the frame-shaped member 7. The sealing portion 12 improves the adhesion between the separator 11 and the frame-shaped member 7 to prevent the fuel or the oxidizing agent from leaking to the outside. The seal portion 12 has an annular shape and is in contact with the frame-shaped member 7 of the joint body 10. Examples of the sealing portion 12 include an O-ring and a rubber sheet. The seal portion 12 may be integrally formed with the separator 11 or the frame-shaped member 7.

(Frame-shaped member 7)
FIG. 2 is a plan view of the fuel cell 100. Further, FIG. 3 is an enlarged cross-sectional view of the fuel cell 100. In addition, in FIG. 2 and FIG. 3, the description of the separator 11 is omitted.

As shown in FIGS. 2 and 3, the frame-shaped member 7 has a frame shape having an opening 71. The frame-shaped member 7 has a rectangular shape in a plan view. The opening 71 has a rectangular shape in a plan view. The joint body 10 is arranged in the opening 71 of the frame-shaped member 7. The frame-shaped member 7 holds the electrolyte membrane 4. Specifically, the frame-shaped member 7 is joined to the electrolyte membrane 4.

The frame-shaped member 7 is made of, for example, a resin, a rubber material, a metal, or the like. Specifically, in the case of a resin, the frame-shaped member 7 is composed of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene propene copolymer (FEP), perfluoroalkoxy alkane (PFA), or the like. can do. In the case of a rubber material, fluororubber can be particularly preferably used for the frame-shaped member 7, for example, vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM) or perfluoroelastomer rubber (FFKM). ) And so on. In the case of metal, the frame-shaped member 7 can be made of austenite-based stainless steel, ferritic stainless steel, titanium (Ti), or the like. Further, the frame-shaped member 7 may be a single material or a composite material made of a plurality of materials (for example, a form in which a resin or a rubber material is coated on the surface of a stainless steel material).

(Joint body 10)
The joint body 10 is arranged in the opening 71 of the frame-shaped member 7 and is held by the frame-shaped member 7. The joint body 10 has a rectangular shape in a plan view. The bonded body 10 includes a cathode 2 (an example of a first electrode), an anode 3 (an example of a second electrode), an electrolyte membrane 4, and a plurality of bent portions 41. The 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)
As shown in FIG. 1, the cathode 2 is arranged on one surface (upper surface of FIG. 1) of the electrolyte membrane 4. The cathode 2 is an anode generally called an air electrode. During power generation of the fuel cell 100, as described above, an _{oxidizing agent containing oxygen (O 2} ) is supplied to the cathode 2 via the gas flow path 111 of the 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-salen, Ni-salen ( 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. Copper-supported carbon (Cu / C) and silver-supported carbon (Ag / C) can be mentioned.

The method for producing the cathode 2 is not particularly limited, but it can be formed, for example, by mixing a cathode catalyst and a carrier if desired with a binder to form a paste, and applying this paste-like mixture to one surface of the electrolyte membrane 4. ..

(Anode 3)
The anode 3 is arranged on the other surface (lower surface of FIG. 1) of the electrolyte membrane 4. The anode 3 is a cathode generally called a fuel electrode. During power generation of the fuel cell 100, fuel containing a hydrogen atom (H) is supplied to the anode 3 via the gas flow path 111 of the separator 11. 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 anode 3 is a cathode generally called a fuel electrode. During power generation of the fuel cell 100, fuel containing a hydrogen atom (H) is supplied to the anode 3 via the gas flow path 111 of the separator 11 as described above.

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 compounds such as (v) hydroxylamines such as 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 catalytic poisoning by carbon monoxide. be.

The fuel compound may be used as it is as a fuel, 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 suitable as the fuel used in the 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 the anode 3 can be formed, for example, by mixing the anode catalyst and, if desired, a carrier with a binder to form a paste, and applying this paste-like mixture to the other surface of the electrolyte membrane 4. ..

(Electrolyte membrane 4)
The electrolyte membrane 4 is arranged in the opening 71 of the frame-shaped member 7. The electrolyte membrane 4 is held by the frame-shaped member 7. The electrolyte membrane 4 is denser than the cathode 2 and the anode 3. For example, the porosity of the electrolyte membrane 4 is about 0 to 7%.

The electrolyte membrane 4 is arranged between the cathode 2 and the anode 3. The electrolyte membrane 4 is connected to each of the cathode 2 and the anode 3. The cathode 2 is arranged on one surface of the electrolyte membrane 4, and the anode 3 is arranged on the other surface. The electrolyte membrane 4 has a rectangular shape in a plan view.

As shown in FIGS. 2 and 3, the cathode 2 is arranged on one surface of the electrolyte membrane 4 in a region other than the outer peripheral edge portion 41. On one side of the electrolyte membrane 4, the outer peripheral edge 41 is exposed from the cathode 2.

Further, on the other surface of the electrolyte 4, the anode 3 is arranged in a region other than the outer peripheral edge portion 41. On the other side of the electrolyte membrane 4, the outer peripheral edge 41 is exposed from the anode 3. That is, neither the cathode 2 nor the anode 3 is arranged on the outer peripheral edge portion 41 of the electrolyte membrane 4. In the present embodiment, the cathode 2 and the anode 3 are formed to have substantially the same size, but the cathode 2 may be larger than the anode 3 or the anode 3 may be larger than the cathode 2.

(Bent portion 42)
The bent portion 42 is arranged on the outer peripheral edge portion of the joint body 10. Specifically, the bent portion 42 is arranged on the outer peripheral edge portion 41 of the electrolyte membrane 4. The bent portion 42 is arranged at a corner of the joint body 10. Specifically, the bent portion 42 is arranged at a corner of the electrolyte membrane 4. In the present embodiment, at least one bent portion 42 is arranged at each corner portion. The bent portion 42 is curved along the corner portion of the electrolyte membrane 4. The plan view shape of the bent portion 42 is, for example, a substantially arc shape.

The bent portion 42 is bent in a ridge shape. In the present embodiment, the bent portion 42 is recessed on one surface of the electrolyte membrane 4 and protrudes on the other surface of the electrolyte membrane 4. That is, the bent portion 42 is bent so as to project toward the anode 3. The bent portion 42 may protrude on one surface of the electrolyte membrane 4 and may be recessed on the other surface of the electrolyte membrane 4. That is, the bent portion 42 may be bent so as to project toward the cathode 2.

The bent portion 42 extends along the direction in which the outer peripheral edge portion of the joint body 10 extends. Specifically, the bent portion 42 extends along the direction in which the outer peripheral edge portion 41 of the electrolyte membrane 4 extends. More specifically, the bent portion 42 extends along the cathode 2 and the anode 3. In this embodiment, the bent portion 42 extends along the corners of the cathode 2 and the anode 3.

The width w of the bent portion 42 can be, for example, about 10 to 2000 μm. Further, the depth d of the bent portion 42 can be, for example, about 1 to 200 μm. The width w of the bent portion 42 can be the width of the protruding portion of the bent portion 42. Further, the depth d of the bent portion 42 can be the depth of the recessed portion of the bent portion 42. The width W and the depth d of the bent portion 44 were measured based on the cross-sectional photographs taken at arbitrary 10 points of the bent portion 42 and orthogonal to the direction in which the bent portion 42 extends as shown in FIG. It can be the average value of the numerical values. The bent portion 42 can be formed by, for example, embossing.

(Details of Electrolyte Membrane 4)
FIG. 4 is a schematic view showing an enlarged cross section of the electrolyte membrane 4. The electrolyte membrane 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, fluororesin (tetrafluorinated resin: PTFE, etc., polyvinylidene fluoride), cellulose, nylon, polyethylene, and the like. Any combination can be mentioned. 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 pores 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. By setting the content within these ranges, the density of the inorganic solid electrolyte body 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. 4, 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 membrane 4 as a whole can be improved.

The inorganic solid electrolyte body 6 has hydroxide ion conductivity. During power generation of the fuel cell 100, the inorganic solid electrolyte body 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 components, 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, for example, derived from 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 body 6 with the porous base material 5 in this way, the strength of the inorganic solid electrolyte body 6 can be improved, so that the inorganic solid electrolyte body 6 can be made thinner. As a result, the resistance of the electrolyte membrane 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 membrane 4 due to the change in the water content of the composite portion 61 during the operation of the fuel cell 100. As a result, it is possible to suppress the generation of stress at the interface between the electrolyte membrane 4 and the cathode 2 and / and the interface between the electrolyte membrane 4 and the anode 3. As a result, it is possible to prevent the electrolyte membrane 4 from peeling off from the cathode 2 and / and the anode 3 and the electrolyte membrane 4 itself from being deformed.

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

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 membrane 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 three. It is possible to prevent the composite portion 61 from peeling off from the porous base material 5 starting from the corner portion made by the person.

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.

The average circle-equivalent diameter of each closed pore 611 is the circle-equivalent diameter of 20 randomly selected pores 611 obtained by observing the cross section of the electrolyte membrane 4 with an electron microscope of 20,000 to 1,500,000 times. Obtained by arithmetic 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 membrane 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. 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 reaction can be stopped before the pores are closed, so that the closed pores 611 can be formed in the composite portion 61. 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 bent portion 42 is formed at a corner portion of the electrolyte membrane 4, but the present invention is not limited to this. For example, as shown in FIG. 5, the bent portion 42 may extend linearly in a portion other than the corner portion of the outer peripheral edge portion 41 of the electrolyte membrane 4. The bent portion 42 may be continuously extended or may be intermittently extended as shown in FIG.

Modification 2
As shown in FIG. 7, the bent portion 42 may extend in an annular shape along the cathode 2. Further, as shown in FIG. 8, a plurality of bent portions 42 may extend from the cathode 2 toward the frame-shaped member 7 at the outer peripheral edge portion 41 of the electrolyte membrane 4. Specifically, the plurality of bent portions 42 may extend radially. Both ends of each bent portion 42 are arranged so as to be spaced apart from the cathode 2 and the frame-shaped member 7, but may be arranged so as to be in contact with at least one of the cathode 2 and the frame-shaped member 7. .. Further, the bent portion 42 extending along the cathode 2 and the bent portion 42 extending radially may be mixed.

Modification 3
As shown in FIGS. 9 and 10, the bent portion 42 may include a plurality of bent portions 42 extending in a plurality of rows. The bent portions 42 extend at intervals from each other. It is preferable that the bent portions 42 extend along each other. In particular, it is preferred that the bent portions 42 extend substantially parallel to each other.

Modification 4
In the above embodiment, the bent portion 42 is arranged only on the outer peripheral edge portion 41, but the arrangement of the bent portion 42 is not limited to this. For example, the bent portion 42 may be formed in the electrolyte membrane 4 over the region where the cathode 2 is formed and the outer peripheral edge portion 41.

Modification 5
As shown in FIG. 11, the bent portion 42 may extend so as to be in contact with at least one of the cathode 2 and the anode 3. That is, the bent portion 42 may pass through the inner peripheral edge of the outer peripheral edge portion 41. For example, the bent portion 42 extends so as to pass through at least one corner of the rectangular cathode 2 and the anode 3.

Modification 6
In the above embodiment, the closed pores 611 are separated from the porous base material 5, but as shown in FIG. 12, 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 membrane 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 membrane 4 and / or the interface between the anode 3 and the electrolyte membrane 4.

Modification 7
In the above embodiment, the electrolyte membrane 4 has a plurality of closed pores 611, but if it has at least one closed pore 611, it is more composite than the case where it does not have any closed pores 611. Since flexibility can be imparted to the portion 61, peeling of the electrolyte membrane 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. 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 electrolyte membrane 4 is a support, but the configuration of the bonded body 10 is not limited to this. For example, as shown in FIG. 13, the cathode 2 may be a support. Specifically, the cathode 2 is arranged in the opening 71 of the frame-shaped member 7. The cathode 2 is held by the frame-shaped member 7. The electrolyte membrane 4 is arranged in a region excluding the outer peripheral edge portion 21 of the cathode 2. In this case, the bent portion 42 is arranged on the outer peripheral edge portion 21 of the cathode 2. The bent portion 42 may not be in contact with the electrolyte membrane 4, or may be in contact with the electrolyte membrane 4. The anode 3 may be a support. In this case, the bent portion 42 is arranged on the outer peripheral edge portion of the anode 3.

A dense layer may be formed on the outer peripheral edge portion 21 of the cathode 2. The dense layer is denser than the cathode 2. For example, the porosity of the dense layer is about 0 to 7%. Further, instead of forming the dense layer, only the outer peripheral edge portion 21 of the cathode 2 may be made dense. For example, the portion of the cathode 2 other than the outer peripheral edge portion 21 may be formed in a porous body, and the outer peripheral edge portion 21 of the cathode 2 may be formed in a dense body.

Modification 12
As shown in FIG. 14, the cathode 2 may be a support, and the electrolyte membrane 4 may be formed on one surface of the cathode 2. The anode 3 is arranged in a region excluding the outer peripheral edge portion 41 of the electrolyte membrane 4. The frame-shaped member 7 holds the cathode 2 and the electrolyte membrane 4. The bent portion 42 is arranged on the outer peripheral edge portion 21 of the cathode 2 and the outer peripheral edge portion 41 of the electrolyte membrane 4.

The anode 3 may be a support. In this case, the electrolyte membrane 4 is formed on the entire surface of the anode 3. The cathode 2 is arranged in a region excluding the outer peripheral edge portion 41 of the electrolyte membrane 4. The frame-shaped member 7 holds the anode 3 and the electrolyte membrane 4. The bent portion 42 is arranged on the outer peripheral edge portion of the anode 3 and the outer peripheral edge portion 41 of the electrolyte membrane 4.

Modification 13
In the above embodiment, the embodiment in which the electrochemical cell according to the present invention is applied to the polymer electrolyte fuel cell has been described, but the object to which the electrochemical cell according to the present invention is applied is not limited to the polymer electrolyte fuel cell. For example, it can be applied to other fuel cells such as polymer electrolyte fuel cells.

Modification 14
In the above embodiment, the cathode 2 corresponds to the first electrode of the present invention and the anode 3 corresponds to the second electrode of the present invention. However, the anode 3 corresponds to the first electrode of the present invention and the cathode 2 corresponds to the present invention. It may correspond to the 2nd electrode of the invention.

2 Cathode 3 Anode 4 Electrolyte film 41 Outer peripheral edge 42 Bent part 5 Porous base material 6 Inorganic solid electrolyte 61 Composite part 62 First film part 63 Second film part 7 Frame-shaped member 71 Opening 10 Joined body

Claims (14)

A frame-shaped member with an opening and
An electrochemical cell joint disposed in the opening of the frame-shaped member and held by the frame-shaped member,
With
The electrochemical cell joint has a plurality of bent portions bent in a ridge shape at the outer peripheral edge portion.
The bent portion extends radially toward the frame-shaped member at the outer peripheral edge portion of the electrochemical cell joint.
The conjugate for an electrochemical cell is
The first electrode held by the frame-shaped member and
An electrolyte membrane arranged in a region excluding the outer peripheral edge portion on one surface of the first electrode, and
Have,
The bent portion is arranged on the outer peripheral edge portion of the first electrode.
The bent portion extends so as to be in contact with the electrolyte membrane.
Electrochemical cell.
The electrochemical cell junction has a second electrode disposed on the electrolyte membrane.
The electrochemical cell according to claim 1.
The bent portion extends radially from the electrolyte membrane toward the frame-shaped member.
The electrochemical cell according to claim 1 or 2.
The joint for an electrochemical cell has a rectangular shape in a plan view, and has a rectangular shape.
The bent portion is arranged at a corner of the electrochemical cell joint.
The electrochemical cell according to any one of claims 1 to 3.
The bent portion extends continuously,
The electrochemical cell according to any one of claims 1 to 4.
The bent portion extends intermittently,
The electrochemical cell according to any one of claims 1 to 4.
The electrolyte membrane is
A porous substrate that has a three-dimensional network structure and forms continuous pores,
An ionic conductor having ionic conductivity and arranged in the continuous pores,
Have,
The electrochemical cell according to any one of claims 1 to 6.
The electrolyte membrane has a first membranous portion that covers the first main surface of the porous base material and a second membranous portion that covers the second main surface of the porous base material.
The electrochemical cell according to claim 7.
The ionic conductor has closed pores inside.
The electrochemical cell according to claim 7 or 8.
The closed pores are separated from the porous substrate.
The electrochemical cell according to claim 9.
The closed pores are in contact with the porous substrate.
The electrochemical cell according to claim 9.
The ionic conductor has a plurality of closed pores including the closed pores.
The electrochemical cell according to any one of claims 9 to 11.
The porous substrate has pores inside and
The pores are impregnated with the ionic conductor.
The electrochemical cell according to any one of claims 7 to 12.
The bent portion projects toward the electrolyte membrane side in the thickness direction.
The electrochemical cell according to any one of claims 1 to 13.

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