JP4984604B2 - Solid oxide fuel cell and method for producing the same - Google Patents

Description

  The present invention relates to a solid oxide fuel cell that generates power using a fuel gas and an oxidant gas, and a method for manufacturing the same.

Conventionally, as a cell design of a solid oxide fuel cell, a flat plate type (stack type), a cylindrical type (tube type), and the like have been proposed. As a shape combining a flat plate and a cylinder, for example, a support substrate having conductivity called lanthanum chromite ceramic is used, or there is a solid oxide fuel cell described in Patent Document 1. The battery of Patent Document 1 has a structure in which a fuel electrode layer, a solid electrolyte layer, and an air electrode layer are combined on a support substrate, and the support substrate mainly includes an iron group metal and / or an iron group metal oxide, A gas permeable and conductive support substrate is used.
JP 2004-146334 A

  However, the lanthanum chromite ceramics as described above is an expensive material, and when a support substrate made of an iron group metal and / or an oxide of an iron group metal is used, the strength is low and the durability is poor. There was a problem that the materials could not be obtained at low cost.

  The present invention has been made to solve the above problems, and an object thereof is to provide a solid oxide fuel cell including a porous substrate having high durability and a method for manufacturing the same.

A single cell in which a fuel electrode and an air electrode are formed on one surface and the other surface of a sheet-like electrolyte, respectively, and the fuel electrode (anode) and air electrode (cathode) of the single cell are supported. A substrate having conductivity and porosity ; and a current collecting layer formed on a surface of the substrate opposite to the electrode. The substrate is made of a ceramic having insulating properties and porosity. And a conductive layer formed along the porous wall surface of the substrate, and the current collecting layer is formed such that at least a part of the substrate is exposed to the outside .

  According to this configuration, the conductive layer is formed along the porous wall surface of the insulating and porous base material, that is, the surface of the base material and the wall surface of the hole extending inside thereof, and thereby the conductive material is electrically connected to the insulating base material. Have sex. Therefore, for example, if an insulating but inexpensive and highly heat-resistant porous material is prepared and a conductive layer is formed thereon, an expensive material or a conductive porous material having low heat resistance is selected. There is no need. That is, a substrate for a solid oxide fuel cell can be formed by appropriately selecting a material according to the purpose, such as an inexpensive material or a material having high heat resistance, and forming a conductive film thereon. .

  Further, if a current collecting layer is formed on the surface of the substrate opposite to the electrode, the current collecting effect can be improved. At this time, it is preferable that at least a part of the substrate is exposed to the outside, and in this way, the current collection layer can prevent the gas from flowing into the substrate from being hindered. .

  In the fuel cell, a hole reaching one of the electrodes can be formed in the substrate. This hole includes a groove shape in addition to the hole shape. By having such a hole reaching one of the electrodes, the gas supplied for power generation can be reliably brought into contact with the electrode through the hole. As a result, the output can be further improved.

  Further, at least one convex portion can be formed on the current collecting layer, and a concave portion can be formed on the substrate, and the convex portion of the current collecting layer can be fitted into the concave portion of the substrate. By doing so, since the convex portion enters the substrate, the distance between the current collecting layer and the electrode can be reduced. As a result, the current collecting ability can be further improved.

In addition, the present invention has been made to solve the above problems, and is any one of a base material made of insulating and porous ceramics, a fuel electrode and an air electrode formed on one surface of the base material. Forming a fuel cell part having one electrode , an electrolyte formed on the one electrode , and the other electrode formed on the electrolyte ; and a metal salt or metal as a metal source on the substrate A step of forming a conductive layer composed of a metal oxide film by contacting a solution for forming a metal oxide film in which a complex is dissolved ; and at least one of the base materials on the other surface of the base material on which the conductive layer is formed. And a step of forming a current collecting layer so that a part is exposed to the outside .

  As described above, when a fuel cell part is formed, and a conductive layer made of a metal oxide film is formed by bringing a metal oxide film forming solution into contact with the base material portion of the fuel cell part, a porous and conductive material is formed. A flexible substrate can be formed. As a method of contacting the metal oxide film forming solution at this time, dipping or spraying can be applied.

  According to the solid oxide fuel cell of the present invention, it is possible to provide a conductive substrate at a low cost.

  Hereinafter, an embodiment of a solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a solid oxide fuel cell according to this embodiment.

  As shown in FIG. 1, the solid oxide fuel cell according to this embodiment includes a single cell 1 including an electrolyte 11, a fuel electrode 12, and an air electrode 13, and a substrate 2 that supports the cell. The single cell 1 is configured by forming a thin-film fuel electrode 12 and an air electrode 13 on both surfaces of an electrolyte 11 formed in a sheet-like rectangle. The substrate 2 has conductivity and porosity, and the single cell 1 is supported on the substrate 2 so that the fuel electrode 12 is in contact with the substrate 2. A current collecting layer 3 is formed on the surface of the substrate 2 opposite to the fuel electrode 12 and the surface of the air electrode 13.

  The substrate 2 is configured by forming a metal oxide film 22 by contacting a porous base material 21 with a metal oxide film forming solution in which a metal salt or a metal complex is dissolved as a metal source. . In addition, although the fuel electrode 12, the air electrode 13, and the board | substrate 2 in FIG. 1 are drawn as the aggregate | assembly of a circular thing, this has shown the porous body. Moreover, it has shown that the current collection layer 3 and the electrolyte 11 are comprised with the precise | minute material. However, the current collecting layer 3 can be formed in a mesh shape to be described later so as not to block the pores of the substrate 2 or can be formed only on a part of the substrate 2, and at least a part of the substrate 2 is a current collecting layer. It is necessary to be configured to be exposed to the outside through the. This is in order not to prevent the gas from flowing into the substrate 2.

  Next, materials constituting the fuel cell will be described. As the material of the electrolyte 11, those known as electrolytes for solid oxide fuel cells can be used. For example, ceria oxide doped with samarium or gadolinium, lanthanum galade doped with strontium or magnesium, etc. Oxygen ion conductive ceramic materials such as oxides, zirconia-based oxides containing scandium and yttrium can be used.

  The fuel electrode 12 and the air electrode 13 can be formed of a ceramic powder material. The average particle size of the powder used at this time is preferably 10 nm to 100 μm, more preferably 50 nm to 50 μm, and particularly preferably 100 nm to 10 μm. In addition, an average particle diameter can be measured according to JISZ8901, for example.

  As the fuel electrode 12, for example, a mixture of a metal catalyst and a ceramic powder material made of an oxide ion conductor can be used. As the metal catalyst used at this time, a material that is stable in a reducing atmosphere, such as nickel, iron, cobalt, or a noble metal (platinum, ruthenium, palladium, etc.) and has hydrogen oxidation activity can be used. In addition, as the oxide ion conductor, one having a fluorite structure or a perovskite structure can be preferably used. Examples of those having a fluorite structure include ceria-based oxides doped with samarium, gadolinium, and the like, and zirconia-based oxides containing scandium and yttrium. In addition, examples of those having a perovskite structure include lanthanum galide oxides doped with strontium and magnesium. Of the above materials, the fuel electrode 12 is preferably formed of a mixture of an oxide ion conductor and nickel. The mixed form of the ceramic material made of the oxide ion conductor and nickel may be a physical mixed form, or may be a powder modification to nickel or a nickel modification to ceramic material. Good. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types. Further, the fuel electrode 12 can also be configured using a metal catalyst alone.

As the ceramic powder material forming the air electrode 13, for example, a metal oxide made of Co, Fe, Ni, Cr, Mn or the like having a perovskite structure or the like can be used. Specifically, (Sm, Sr) CoO ₃ , (La, Sr) MnO ₃ , (La, Sr) CoO ₃ , (La, Sr) (Fe, Co) O ₃ , (La, Sr) (Fe, Co , Ni) O _{3 and the} like, and (La, Sr) (Fe, Co) O ₃ is preferable. The ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

The current collecting layer 3 is made of a conductive metal such as Pt, Au, Pd, Ag, Ni, Cu, or SUS, or a metal-based material, or La (Cr, Mg) O ₃ , (La, Ca) CrO ₃ , (La , Sr) CrO ₃ and other conductive ceramic materials such as lanthanum and chromite, and one of these may be used alone, or two or more may be used in combination. Also good.

  The electrolyte 11, the fuel electrode 12, and the air electrode 13 are formed by adding appropriate amounts of a binder resin, an organic solvent, and the like with the above-described material as a main component. More specifically, it is preferable to add a binder resin or the like so that the main component is 50 to 95% by weight in the mixing of the main component and the binder resin. Further, as described above, the current collecting layer paste is also formed by adding an appropriate amount of a binder resin, an organic solvent, or the like.

  As a method of forming the electrolyte 11, the fuel electrode 12, the air electrode 13, and the current collecting layer 2, for example, a printing method can be used. Specifically, a screen printing method, a knife coating method, a doctor blade method, a spray coating method can be used. Or the like can be used. In addition, the electrode can be formed by applying the fuel electrode 12, the air electrode 13, and the current collecting layer 2 on a sheet (so-called green body) and transferring them. Further, the current collecting layer 3 may be formed in a mesh shape in advance and pressed onto the electrode. At this time, for example, the current collecting layer 3 attached to the substrate 2 on the fuel electrode 12 side can be made of a mesh made of platinum, and the current collecting layer attached to the air electrode 13 can be made of a mesh made of gold.

  Next, a method for manufacturing a substrate will be described. In the metal oxide film manufacturing method according to the present embodiment, a metal oxide film is obtained by bringing a metal oxide film forming solution in which a metal salt or a metal complex is dissolved as a metal source into contact with a substrate surface. A method for manufacturing a physical film, wherein the metal oxide film forming solution contains a reducing agent. Here, the “base material surface” means the outermost surface of the base material, and does not mean a catalyst layer or the like obtained on the base material by a catalytic treatment or the like. Moreover, the outermost surface of the base material in the porous base material extends not only to the upper side, the lower side, and the lateral side of the porous base material but also to the inside. The manufacturing process can be simplified by bringing the metal oxide film-forming solution into contact with the surface of the substrate and forming the metal oxide film directly on the surface of the substrate. In addition, the “metal complex” referred to here includes a metal ion coordinated with an inorganic substance or an organic substance, or a so-called organometallic compound having a metal-carbon bond in the molecule.

Regarding the mechanism of the manufacturing method of such a metal oxide film, cerium oxide is used by using cerium nitrate (Ce (NO ₃ ) ₃ ) as a metal source and borane-dimethylamine complex (also known as dimethylamine borane, DMAB) as a reducing agent. The case where a (CeO ₂ ) film is formed will be described.

The cerium oxide film is not yet clear, but is considered to be formed by the following six equations.
(I) Ce (NO ₃ ) ₃ → Ce ³⁺ + 3NO ^{3 −}
(Ii) (CH ₃ ) ₂ NHBH ₃ + 2H ₂ O → BO ² + (CH ₃ ) ₂ NH + 7H ⁺ + 6e ⁻
(Iii) 2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂
(Iv) Ce ³⁺ → Ce ⁴⁺ + e ⁻
(V) Ce ⁴⁺ + 2OH ⁻ → Ce (OH) ₂ ²⁺
(Vi) Ce (OH) ₂ ²⁺ → CeO ₂ + H ₂
Such a mechanism will be specifically described. First, cerium nitrate and DMAB are dissolved in water as a solvent to prepare a metal oxide film forming solution, and the base material 21 is immersed in this solution. At this time, cerium nitrate becomes cerium ions in the aqueous solution (formula (i)). Subsequently, the reducing agent DMAB decomposes (formula (ii)) to release electrons. Thereafter, the emitted electrons induce water electrolysis (formula (iii)) to generate hydroxide ions and raise the pH of the metal oxide film forming solution. As a result, the cerium ion changes the valence (formula (iv)) and further reacts with the generated hydroxide ion (formula (v)) to produce Ce (OH) ₂ ²⁺ . Thereafter, Ce (OH) ₂ ^{2+ in the} vicinity of the substrate 2 becomes CeO ₂ due to a local increase in pH (formula (vi)). And the cerium oxide film | membrane 22 is formed by repeating reaction of (ii)-(vi) Formula.

Moreover, it can be considered that the above reaction caused Ce ³⁺ produced by the formula (i) to reach the CeO ₂ region due to the pH increase by the hydroxide ions produced by the formula (iii). From this, it is considered that a metal oxide film can be similarly manufactured by the manufacturing method of the present invention as long as it is a metal element having a similar metal oxide region. Moreover, even if it is a metal element which has a metal hydroxide area | region, a metal oxide film is obtained by heating a metal hydroxide film | membrane. In the present invention, even when an alcohol, an organic solvent, or the like is used as a solvent instead of water, a metal oxide film is formed by a reaction similar to the above reaction or a trace amount of water contained in the solvent. I think that.

  Hereafter, the manufacturing method of the metal oxide film (conductive layer) of this invention is demonstrated in detail for every structure.

1. Metal Oxide Film Forming Solution First, the metal oxide film forming solution used in the present invention will be described. The metal oxide film forming solution used in the present invention contains at least a reducing agent, a metal salt or metal complex as a metal source, and a solvent.

(1) Reducing agent The reducing agent used in the present invention has a function of releasing electrons by a decomposition reaction, generating hydroxide ions by water electrolysis, and raising the pH of the metal oxide film forming solution. It is. By raising the pH and inducing the metal oxide region or the metal hydroxide region in the Pourbaix diagram, it is possible to create an environment in which a metal oxide film is easily generated.

  The concentration of the reducing agent in the metal oxide film forming solution used in the present invention varies depending on the type of the reducing agent, but is usually 0.001 to 1 mol / l, particularly 0.01 to It is preferably 0.1 mol / l. When the concentration is below the above range, the metal oxide film formation reaction is difficult to occur, and there is a possibility that a sufficient film formation rate cannot be obtained. When the concentration is above the above range, the obtained effect is largely different. This is because it is not preferable in terms of cost.

  Such a reducing agent is not particularly limited as long as it can be dissolved in a solvent described later and can release electrons by a decomposition reaction. For example, borane-tert-butylamine complex, borane- Examples thereof include borane complexes such as N, N diethylaniline complex, borane-dimethylamine complex, borane-trimethylamine complex, sodium cyanoborohydride, sodium borohydride, etc. Among them, it is preferable to use borane complex. .

(2) Metal Source The metal source used in the present invention is dissolved in a metal oxide film forming solution and gives a metal oxide film by the action of a reducing agent or the like. The metal source used in the present invention may be a metal salt or a metal complex as long as it dissolves in a solvent described later.

  The concentration of the metal source in the metal oxide film forming solution used in the present invention is usually 0.001 to 1 mol / l, particularly 0.01 to 0.1 mol / l when the metal source is a metal salt. When the metal source is a metal complex, it is usually 0.001 to 1 mol / l, and particularly preferably 0.01 to 0.1 mol / l. If the concentration is below the above range, the metal oxide film formation reaction is difficult to occur, and a desired metal oxide film may not be obtained. If the concentration is above the above range, a precipitate is formed. Because there is a possibility.

  The metal element constituting such a metal source is not particularly limited as long as a desired metal oxide film can be obtained. For example, Mg, Al, Si, Ca, Ti, V, Mn, Fe , Co, Ni, Cu, Zn, Y, Zr, Ag, In, Sn, Ce, Sm, Pb, La, Hf, Sc, Gd, and Ta are preferably selected. Since the metal element has a metal oxide region or a metal hydroxide region in the Pourbaix diagram, it is suitable as a main constituent element of the metal oxide film.

  Specific examples of the metal salt include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates and the like containing the metal elements. Among these, in the present invention, it is preferable to use chlorides, nitrates, acetates and the like. This is because these compounds are easily available as general-purpose products.

  Specific examples of the metal complex include magnesium diethoxide, aluminum acetylacetonate, calcium acetylacetonate dihydrate, calcium di (methoxyethoxide), calcium gluconate monohydrate, citric acid Calcium tetrahydrate, calcium salicylate dihydrate, titanium lactate, titanium acetylacetonate, tetraisopropyl titanate, tetranormal butyl titanate, tetra (2-ethylhexyl) titanate, butyl titanate dimer, titanium bis (ethylhexoxy) bis (2 -Ethyl-3-hydroxyhexoxide), diisopropoxytitanium bis (triethanolaminate), dihydroxybis (ammonium lactate) titanium, diisopropoxytitanium bis (ethylacetate) Toacetate), titanium peroxo ammonium citrate tetrahydrate, dicyclopentadienyl iron (II), iron lactate (II) trihydrate, iron (III) acetylacetonate, cobalt (II) acetylacetonate , Nickel (II) acetylacetonate dihydrate, copper (II) acetylacetonate, copper (II) dipivaloylmethanate, copper (II) ethylacetoacetate, zinc acetylacetonate, zinc lactate trihydrate , Zinc salicylate trihydrate, zinc stearate, strontium dipivaloylmethanate, yttrium dipivaloylmethanate, zirconium tetra-n-butoxide, zirconium (IV) ethoxide, zirconium normal propyrate, zirconium normal butyrate , Zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zir Nitroacetylacetonate bisethylacetoacetate, zirconium acetate, zirconium monostearate, penta-n-butoxyniobium, pentaethoxyniobium, pentaisopropoxyniobium, tris (acetylacetonato) indium (III), indium 2-ethylhexanoate (III), tetraethyltin, dibutyltin oxide (IV), tricyclohexyltin (IV) hydroxide, lanthanum acetylacetonate dihydrate, tri (methoxyethoxy) lanthanum, pentaisopropoxytantalum, pentaethoxytantalum, tantalum ( V) Ethoxide, cerium (III) acetylacetonate n-hydrate, lead (II) citrate trihydrate, lead cyclohexanebutyrate and the like. Among them, in the present invention, magnesium diethoxide, aluminum acetylacetonate, calcium acetylacetonate dihydrate, titanium lactate, titanium acetylacetonate, tetraisopropyl titanate, tetranormal butyl titanate, tetra (2-ethylhexyl) titanate , Butyl titanate dimer, diisopropoxy titanium bis (ethylacetoacetate), iron (II) lactate trihydrate, iron (III) acetylacetonate, zinc acetylacetonate, zinc lactate trihydrate, strontium dipivaloyl Methanate, pentaethoxyniobium, tris (acetylacetonato) indium (III), indium (III) 2-ethylhexanoate, tetraethyltin, dibutyltin oxide (IV), lanthanum acetylacetonate dihydrate , It is preferable to use tri (methoxyethoxy) lanthanum, cerium (III) acetylacetonate n-hydrate.

In the present invention, the metal oxide film forming solution may contain two or more kinds of the above metal elements. By using a plurality of kinds of metal elements, for example, ITO, Gd—CeO ₂ , Sm A composite metal oxide film such as —CeO ₂ or Ni—Fe ₂ O ₃ can be obtained.

(3) Solvent The solvent used in the present invention is not particularly limited as long as it can dissolve the reducing agent and the metal source described above. For example, when the metal source is a metal salt, Examples thereof include water, methanol, ethanol, isopropyl alcohol, propanol, butanol and the like, lower alcohols having a total carbon number of 5 or less, toluene, and mixed solvents thereof. When the metal source is a metal complex, water, the above-mentioned And lower alcohols, toluene, and mixed solvents thereof. In the present invention, the above solvents may be used in combination. For example, a metal complex having low solubility in water but high solubility in an organic solvent, and low solubility in an organic solvent, but water In the case of using a reducing agent having a high solubility in water, water and an organic solvent are mixed to dissolve both of them, and a uniform metal oxide film forming solution can be obtained.

(4) Additive The solution for forming a metal oxide film used in the present invention may contain additives such as an auxiliary ion source and a surfactant.

  The auxiliary ion source generates hydroxide ions by reacting with electrons, and can raise the pH of the solution for forming a metal oxide film to make it easy to form a metal oxide film. The amount of the auxiliary ion source used is preferably appropriately selected according to the metal source and the reducing agent to be used.

Specific examples of such auxiliary ion sources include chlorate ions, perchlorate ions, chlorite ions, hypochlorite ions, bromate ions, hypobromate ions, nitrate ions, and nitrite ions. An ionic species selected from the group consisting of These auxiliary ion sources are believed to cause the following reactions in solution.
_{^{ClO 4- + H 2 O + 2e}} - ⇔ ClO 3- + 2OH -
_{^{ClO 3- + H 2 O + 2e}} - ⇔ ClO 2- + 2OH -
ClO ² + H ₂ O + 2e ⁻ Ｃｌ ClO ⁻ + 2OH ^{−
_{2ClO - + 2H 2 O + 2e}} - ⇔ Cl 2 (g) + 4OH -
_{^{BrO 3- + 2H 2 O + 4e}} - ⇔ BrO - + 4OH -
_{^{2BrO - + 2H 2 O + 2e}} - ⇔ Br 2 + 4OH -
NO ³ + H ₂ O + 2e ⁻ ⇔ NO ² + + 2OH ⁻
NO ² + 3H ₂ O + 3e ⁻ ⇔ NH ₃ + 3OH ⁻
2. Next, the base material on which the metal oxide film is formed will be described. The material of the base material 2 used here is not particularly limited, but a ceramic material is used because it needs to be durable enough to withstand the operating temperature of the solid oxide fuel cell of 800 ° C. or higher. It is preferable to do. For example, it is preferable to use alumina, zirconia, titania, silica or the like that has high durability and is relatively inexpensive. Moreover, it is preferable that the material of the base material is appropriately selected in consideration of the corrosion resistance imparted by the metal oxide film, the strength, the use of the member, and the like.

  Further, the substrate used here is not particularly limited, for example, those having a smooth surface, those having a fine structure, those having a hole, those having grooves, A thing with a flow path, a thing with a porous thing, and a thing provided with a porous membrane may be used. Among them, in the present invention, it is preferable that the substrate has a fine structure, is porous, and is provided with a porous film. This is because the solution for forming a metal oxide film can penetrate into the inside of the base material, and a metal oxide film having good shape following ability can be obtained.

3. Next, a contact method between the substrate and the metal oxide film forming solution in the method for producing a metal oxide film of the present invention will be described. The contact method in the present invention is not particularly limited as long as it is a method in which the above-described base material and the above-described metal oxide film forming solution are brought into contact with each other, and specifically, roll coating method, dipping And a single-wafer method, a method of applying the solution in a mist, and the like.

  For example, the roll coating method is a method of forming a metal oxide film on the surface of the base material by passing the base material 2 between the rolls, for example, for continuous metal oxide film production. Is suitable. The dipping method is a method of forming a metal oxide film on the surface of the substrate by immersing the substrate in a solution for forming a metal oxide film. For example, the entire substrate 21 is formed with a metal oxide film. A metal oxide film can be formed on the entire surface of the substrate 21 by immersing in the solution.

3-1. In the present invention, heating is preferably performed when the substrate surface and the metal oxide film forming solution are brought into contact with each other. By heating, the decomposition reaction of the reducing agent can be promoted, and the film formation rate can be improved. The method for heating is not particularly limited as long as it can improve the deposition rate of the metal oxide film, but heating the substrate is particularly preferable, and the substrate and the metal oxide are particularly preferable. It is preferable to heat the physical film forming solution. This is because the decomposition reaction of the reducing agent in the vicinity of the substrate can be promoted.

  Such a heating temperature is preferably appropriately selected in accordance with the characteristics of the reducing agent to be used and the base material. Specifically, the heating temperature is preferably in the range of 50 to 150 ° C, and more preferably 70 to 100 ° C. It is more preferable to be within the range.

4). Next, a metal oxide film obtained by the method for producing a metal oxide film of the present invention will be described. Since the method for producing a metal oxide film of the present invention is a wet coating using a metal oxide film forming solution, for example, even in the case of a substrate having a porous substrate or a porous body, the metal The oxide film forming solution can easily penetrate into the porous body and the like, and a uniform metal oxide film can be obtained. Note that the obtained metal oxide film may be conductive in itself, or may be conductive by being reduced in a reducing atmosphere during power generation. . For example, NiO in Examples described later becomes Ni by reduction and becomes conductive.

  The fuel cell configured as described above generates power as follows. First, a fuel gas composed of hydrogen or a hydrocarbon such as methane or ethane and an oxidant gas such as air are supplied to the unit cell 1 at a high temperature (for example, 400 to 1000 ° C.) to the fuel electrode and the air electrode, respectively. . At this time, it is necessary to provide a threshold or the like so that the two gases are not mixed. As a result, the oxidant gas contacts the air electrode 13 via the current collecting layer 3, and the fuel gas contacts the fuel electrode 12 via the current collecting layer 3 and the substrate 2. Thus, since the fuel electrode 12 and the air electrode 13 are in contact with the mixed gas, oxygen ion conduction through the electrolyte 11 occurs between the fuel electrode 12 and the air electrode 13 in each unit cell 1 to generate power. .

  As described above, according to the present embodiment, the metal oxide film 22 is formed along the porous wall surface of the insulating and porous base material 2, that is, along the surface of the base material 21 and the wall surface of the hole extending inside. This makes the insulating base material conductive. Thus, for example, if an insulating material is provided that is inexpensive and highly porous with high heat resistance, and a metal oxide film 22 is formed thereon, an expensive material or a conductive porous material with low heat resistance can be obtained. No need to make a choice. That is, a substrate for a solid oxide fuel cell can be formed by appropriately selecting a material according to the purpose, such as an inexpensive material or a material having high heat resistance, and forming a metal oxide film thereon. it can.

  In addition, as a method of manufacturing the fuel cell, for example, after the single cell 1 including the electrolyte 11, the fuel electrode 12, and the air electrode 13 is manufactured and the base material 21 is attached thereto (the present invention so far). The metal oxide film 22 may be formed on the substrate 21. Alternatively, the fuel electrode 12, the electrolyte 11, and the air electrode 13 may be formed on the base material 21 in this order by printing or the like, and then the metal oxide film 22 may be formed on the base material 21. The current collecting layer 3 is finally formed on the substrate side and the air electrode side.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A various change is possible unless it deviates from the meaning. For example, as shown in FIG. 2, a groove 23 reaching the fuel electrode 12 can be formed in the substrate 2. When the groove 23 reaching the fuel electrode 12 is provided, the gas supplied for power generation can be reliably brought into contact with the fuel electrode 12 through the groove 23. As a result, the output can be further improved.

  Further, as shown in FIG. 3, at least one convex portion 31 is formed on the current collecting layer 3, and a concave portion is formed on the substrate 2, and the convex portion 31 of the current collecting layer 3 is fitted into the concave portion of the substrate 2. Can be configured to. By doing so, since the convex portion 31 enters the inside of the substrate 2, the distance between the current collecting layer 3 and the fuel electrode 12 can be reduced. As a result, the current collecting ability can be further improved. In addition, the convex part 31 of the current collection layer 3 can be formed by supplying the material for current collection layers with a dispenser etc. with respect to the recessed part of the board | substrate 2, for example.

  In the above embodiment, the so-called single-chamber fuel cell that supplies the mixed gas of the fuel gas and the oxidant gas has been described. It is also possible to configure as a so-called two-chamber type that supplies the gas.

  Hereinafter, an example of a method for forming a substrate according to the present invention will be described. However, the present invention is not limited to this.

Dipping 1
Subsequently, nickel nitrate (manufactured by Kanto Chemical Co., Inc.) and borane-dimethylamine complex (manufactured by Kanto Chemical Co., Ltd.), which is a reducing agent, are mixed with water so that the respective concentrations become 0.01 mol / liter and 0.01 mol / liter. And a solution for forming a metal oxide film was prepared by dissolving in a mixed solvent composed of ethanol. The mixed solvent used had a volume ratio (water: ethanol) of 50:50. And the alumina porous board was immersed in the said metal oxide film formation solution (70 degreeC) for 20 hours, and the NiO metal oxide film (thickness: 0.1 micrometer) which covers an alumina porous board was formed.

Dipping 2
Next, borane-trimethylamine complex as a reducing agent (manufactured by Kanto Chemical Co., Inc.) was added to 1000 g of an aqueous solution of 0.03 mol / l indium chloride and 0.001 mol / l tin chloride so as to be 0.1 mol / l. . Further, 2 g of sodium chlorate was added to the above solution as an auxiliary ion source to obtain a metal oxide film forming solution.

  Next, the alumina porous plate was immersed in the above solution at a temperature of 70 ° C. for 12 hours. At this time, the metal oxide film forming solution was circulated and passed through a filter to eliminate precipitates and contaminated dust. As a result, a metal oxide film was obtained on the substrate. Thereafter, it was washed with pure water, dried at 100 ° C. for 1 hour, and further fired at 350 ° C. for 1 hour.

Spray solution nickel acetylacetonate (manufactured by Kanto Chemical Co., Inc.) was dissolved in a mixed solvent consisting of toluene and ethanol so as to have a concentration of 0.1 mol / liter to prepare a metal oxide film forming solution. The mixed solvent used had a volume ratio (toluene: ethanol) of 85:15. Then, in a state where the alumina porous plate is heated to 500 ° C., the metal oxide film forming solution (500 ml) is sprayed with an ultrasonic nebulizer (NE-U17 manufactured by OMRON Corporation) and is brought into contact with the alumina porous plate. A NiO metal oxide film (thickness: 1 μm) was formed.

1 is a cross-sectional view of a solid oxide fuel cell according to an embodiment of the present invention. It is sectional drawing which shows the other example of the fuel cell of FIG. FIG. 6 is a cross-sectional view showing still another example of the fuel cell in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single cell 11 Electrolyte 12 Fuel electrode 13 Air electrode 2 Board | substrate 21 Base material 22 Metal oxide film 3 Current collection layer

Claims (4)

A single cell in which a fuel electrode and an air electrode are respectively formed on one side and the other side of a sheet-like electrolyte;
A substrate supporting any one of the fuel electrode and the air electrode of the single cell, and having conductivity and porosity;
A current collecting layer formed on a surface of the substrate opposite to the electrode;
With
The substrate has a base material made of ceramic having insulating properties and porosity, and a conductive layer formed along the porous wall surface of the base material ,
The current collecting layer is a solid oxide fuel cell formed such that at least a part of the substrate is exposed to the outside . The solid oxide fuel cell according to claim 1 , wherein the substrate has a hole reaching the one electrode. The solid oxide fuel cell according to claim 1 , wherein the current collecting layer has at least one convex portion, and the convex portion is fitted in a concave portion formed in the substrate. A base material made of insulating and porous ceramics, one of a fuel electrode and an air electrode formed on one surface of the base material, an electrolyte formed on the one electrode, and the electrolyte forming a fuel cell part having the other electrode, which is formed on,
Contacting the base material with a metal oxide film-forming solution in which a metal salt or metal complex is dissolved as a metal source to form a conductive layer made of a metal oxide film ;
Forming a current collecting layer on the other surface of the base material on which the conductive layer is formed so that at least a part of the base material is exposed to the outside;
A method for producing a solid oxide fuel cell comprising:

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