JP5410076B2 - Conductive laminate and method for producing conductive laminate - Google Patents

Description

    The present invention relates to a conductive laminate having a novel structure including an inorganic base and a conductive layer (conductive film) and a method for producing the same. In particular, the present invention relates to a conductive laminate suitable for forming a current collector in a solid oxide fuel cell and a method for manufacturing the same.

  Here, the current collector in the fuel cell will be described as an example, but the application of the conductive laminate of the present invention is not limited to this, and of course, other electrochemical reactors having the same configuration may have other configurations. The present invention can also be applied to products having a conductive laminate structure.

  In this specification, unless otherwise specified, “%” means “mass%” and “part” means “part by mass”.

  Conventionally, a current collector (current collection layer) in a solid oxide fuel cell (SOFC) has been formed of a conductive film formed of a porous structure containing metal (for example, Patent Documents 1 and 2). Etc.). The reason is as follows.

  The resistance of the electrode in the fuel cell as described above depends on the overvoltage generated in the process in which the charge generated by the electrode reaction at the three-phase interface (electrolyte / gas / electrode) moves across the interface and the effective reaction area of the electrode. Inward resistance becomes a problem.

  For example, when a honeycomb interconnector can be formed only on the end face of an electrode, electrons at a long distance cannot run, causing an IR loss and making it difficult for current to flow.

  Then, if the conductive film, which is a porous structure, is stacked on the electrode as a current collector, and the current collector is connected to the interconnector, the current generated at the three-phase interface can be collected without relying on the electrode material. it can.

  In addition, since the electrode material (for example, nickel oxide) on the anode side (usually the fuel electrode) is reduced during power generation to become a metal and its resistance is reduced, its omission may be considered if the electrode has a certain thickness. However, the electrode material on the cathode side (usually the air electrode) is an oxide (for example, lanthanum manganite), and its resistance is large, and usually a current collector needs to be laminated.

  And the current collector in SOFC is required to have the following characteristics.

  1) Air (oxygen) or fuel gas permeation must be easy. That is, good gas permeability is required.

  2) It must be in close contact with the electrode material.

3) Must be heat resistant to withstand the operating temperature of SOFC (600-800 ° C)
4) It can be manufactured at low cost.

  Patent Document 3 describes the following technique relating to a conductive structure having a three-dimensional network structure (porous).

  The conductive structure has a three-dimensional network skeleton including a noble metal such as platinum, and the maximum length of the diameter of the transverse cut surface of the skeleton is 100 nm or less. The structure includes a first step of preparing a film in which a first material including a noble metal is dispersed in a second material, and removing the second material in the film by dry etching It is manufactured through the second step.

  However, the conductive structure is not the μm level porous structure of the present invention, but the conductive fine structure scheduled to be applied to a nanometer level membrane electrode that requires catalytic performance and electronic conductivity in a fuel cell. It is related to the structure and is heterogeneous.

  Patent Document 2 discloses an invention of a conductive composition containing a particulate silver compound and a resin binder. The conductive composition is applied to an arbitrary object and then heated to form a conductive film.

However, unlike the present invention, it is not planned to form a porous structure having a continuous three-dimensional network skeleton.
JP 2008-53095 A (Claims etc.) JP 2004-303478 A (Claims etc.) JP 2007-44675 A (Claims etc.) Japanese Patent No. 3949658 (claims, etc.)

  In view of the above, the present invention is suitable for forming a current collector (conductive film) in a fuel cell or the like that is not described in the above-mentioned patent documents, that is, a conductive material having a novel structure that can be manufactured with good productivity. An object of the present invention is to provide a conductive laminate and a method for producing the same.

  The conductive laminate according to the present invention is a conductive laminate comprising an inorganic base and a conductive film, wherein the conductive film is in direct contact with the inorganic base and has a porous structure with a thickness of 10 to 1000 μm. The porous structure includes a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side.

  The conductive film in the conductive laminate in the present invention is a porous structure having a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side. Even if a part or the whole is covered, the gas or liquid can pass through the conductive film.

  The conductive laminate according to the present invention has a structure in which 1) an inorganic base is a fuel electrode and / or an air electrode formed on a solid electrolyte in a solid oxide fuel cell, and the conductive film is a current collector. 2) The inorganic base is an oxidation electrode and / or a reduction electrode formed on a solid electrolyte in a solid oxide electrochemical reactor, and the conductive film is a current collector or a power distribution body. be able to.

  In addition, the said electrical power collector and electric power distribution body are joined to the fuel electrode or the air electrode (oxidation electrode or reduction electrode), and must have the function to distribute an electron to these electrodes, or the function to collect an electron. . Further, the current collector and the power distribution body must be capable of transmitting the gas supplied to these electrodes or the gas generated at these electrodes. The conductive film in the present invention has a function necessary for the current collector.

  It is desirable that the conductive metal contained in the conductive film contains one kind or two or more kinds of metals and / or alloys selected from silver, platinum, and nickel. This is because these metals are excellent in conductivity and corrosion resistance.

  Moreover, it is desirable that the conductive film of the conductive laminate according to the present application has a plurality of cracks having a width of 10 to 500 μm (desirably 20 to 300 μm, more desirably 50 to 200 μm) on the surface layer. In the portion where the surface layer of the conductive film is cracked, the thickness of the layer is thinner than the portion where the crack is not cracked, gas is easily transmitted, and the conductive film is excellent in gas permeability.

  That is, when the conductive film having cracks is used as the current collector or power distribution body, gas permeability is improved, and the power generation reaction of the fuel cell and the oxidation-reduction reaction of the electrochemical reactor are promoted.

  If the width of the crack is too small, the conductive film tends to be inferior in gas permeability. Conversely, if the width of the crack is too large, the continuity of the conductive film is impaired and the conductivity is lowered.

  The area ratio of the crack portion in the surface area of the conductive film (including the area of the crack portion) is desirably 5 to 60%. More preferably, it is 10 to 50%, optimally 15 to 45%. If the area ratio of the crack portion is too small, the effect of the crack is not sufficient, and if it is excessive, sufficient conductivity may not be obtained.

  Note that cracks are generated in the surface layer of the conductive film, and the conductive film maintains continuity in the deep layer portion. Therefore, even if the conductive film has cracks, the conductivity of the conductive laminate is impaired. I can't.

  The method for producing the conductive laminate includes 1) a step of preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent; and 2) applying the slurry composition to an inorganic base. Forming a coating film, and 3) heating or baking the coating film to eliminate the organic polymer in the coating film. According to this manufacturing method, it is possible to simultaneously form a porous conductive film containing a conductive metal and having a continuous three-dimensional network skeleton and bonding the conductive film to an inorganic base. In addition, the conductive film of the conductive laminate formed by the above method does not include an organic polymer, and is formed only of an inorganic component such as an inorganic component generated by thermally decomposing a conductive metal and an organic polymer. Yes.

  In addition, another method for producing the conductive laminate includes 1) a step of preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent, and 2) an inorganic slurry composition. A step of coating the substrate to form a coating film; 3) a step of drying the coating film to obtain a dry coating film of the slurry composition; and 4) heating or baking the dried coating film to form the organic coating. And a step of causing the molecules to disappear, and the organic polymer is cracked in the dry coating film as having high film-forming properties capable of generating cracks during heating or firing.

  Here, the film-forming property refers to the property of forming a uniform phase (film) in which the components of the organic polymer are fused when the coating film of the slurry composition is dried or heated.

  In addition, by using one or two or more kinds of metals and / or alloys selected from silver, platinum and nickel as the conductive metal contained in the slurry composition, the conductivity is excellent in conductivity and corrosion resistance. A conductive laminate having a film can be formed. Further, when silver particles having an average particle diameter of 1 to 200 μm and a purity of 85% or more are used as the metal and / or alloy, the conductive film is particularly excellent in conductivity.

  Moreover, the adhesion between the conductive film and the inorganic base becomes strong by including an inorganic binder in the slurry composition.

  According to the present invention, a conductive laminate in which a porous conductive film is directly bonded to and laminated on an inorganic base, and formation of the porous conductive film and bonding of the conductive film to the inorganic base are performed. The manufacturing method of the electroconductive laminated body which can be performed simultaneously can be provided.

  The conductive laminate of the present invention is a conductive laminate comprising an inorganic base and a conductive film containing a conductive metal, wherein the conductive film is in direct contact with the inorganic base. A porous structure having a thickness of 1000 μm is provided with a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side.

  The inventor of the present invention provides a conductive laminate in which a conductive plate having a width of 30 mm × length of 50 mm × thickness of about 100 μm is laminated on the surface of a ceramic plate as an inorganic base. Produced. The conductive film had conductivity and was directly bonded to the ceramic plate. Further, when the conductive film was observed with a microscope and magnified 100 times, the shape of the porous body was a porous body having a continuous three-dimensional network skeleton. The ceramic plate was a plate-like sintered body formed by firing zirconia as a ceramic powder.

  The conductive film is formed with a thickness of about 100 μm, but the thickness is not particularly limited, and is usually in the range of 10 to 1000 μm, preferably 20 to 500 μm.

  However, if the thickness of the conductive film is too thin, the continuity of the three-dimensional network skeleton cannot be maintained, and the required conductivity is difficult to obtain. If the thickness of the conductive film is too thick, the three-dimensional network skeleton becomes a resistance to gas permeation, making it difficult to obtain sufficient gas permeability.

  The conductive metal contained in the conductive film is not limited to silver, but various metals such as silver, platinum, gold, copper, palladium, iridium, aluminum, chromium, indium, nickel, copper, iron, and zinc. And alloys containing various metals. Among these, in consideration of conductivity and corrosion resistance, a metal selected from silver, platinum and nickel, or an alloy containing a metal selected from silver, platinum and nickel is preferable. Further, among them, silver or an alloy containing silver is particularly preferable in consideration of excellent conductivity. The conductive film preferably contains 90% or more (more preferably 95% or more) of a conductive metal from the viewpoint of conductivity.

  The inorganic base serves as a base on which the conductive film is installed, and is not limited to the ceramic plate of the zirconia sintered body. For example, firing ceramic compositions using oxide ceramics such as alumina, mullite and cordierite, nitride ceramics such as silicon nitride, aluminum nitride and boron nitride, or carbide ceramics represented by silicon carbide. Examples thereof include a ceramic plate formed by ligation and a ceramic structure. Furthermore, there may be an inorganic plate or an inorganic structure formed of an inorganic composition containing glass, metal, cement, gypsum, glass, metal or the like as an inorganic binder.

  The conductive film may be, for example, a surface of a fuel electrode or an air electrode formed on a solid electrolyte of a solid oxide fuel cell (SOFC), or an oxidation electrode or reduction formed on a solid electrolyte in an electrochemical reactor. You may install in the surface of an electrode.

  The SOFC has a fuel electrode on one side with a solid electrolyte in between, an air electrode on the other side, fuel gas on the fuel electrode side, oxidant gas on the air electrode side, and electrolyte A power generator that generates electricity by electrochemically reacting a fuel and an oxidant. A fuel gas is supplied to the fuel electrode side, an oxidant gas is supplied to the air electrode side, and the fuel electrode and the air electrode are connected by an electric circuit, whereby a current flows through the electric circuit.

  For example, when power is generated using hydrogen as the fuel gas and oxygen as the oxidant gas, the following reaction occurs between the fuel electrode and the air electrode.

Fuel electrode H ₂ + O ²⁻ → H ₂ O + 2e ⁻
Air electrode 1 / 2O ₂ + 2e ⁻ → O ²⁻
In this reaction, electrons (e ⁻ ) generated at the fuel electrode move to the air electrode through the electric circuit and are used for the reaction at the air electrode. Further, oxygen ions (O ²⁻ ) generated at the air electrode permeate the solid electrolyte and move to the fuel electrode, and are used for the reaction at the fuel electrode. In this way, electrons flow through the electric circuit to generate electricity. The air electrode and the fuel electrode are layers made of a substance that serves as a catalyst for the reaction.

  The reaction at the fuel electrode and the air electrode is performed at the interface of three kinds of substances, that is, a catalyst, a solid electrolyte, and a gas. Since this reaction is performed on the entire surface of the portion where the fuel electrode and air electrode layers are provided, in order to increase the power generation efficiency of the fuel cell, the electrons generated at the fuel electrode are collected and the entire air electrode is collected. Need to distribute electrons. Therefore, a conductor called a current collector may be disposed on the surface of the fuel electrode or the air electrode. By installing the current collector, electrons generated at various locations in the fuel electrode layer are collected through the current collector, pass through the electronic circuit, and then distributed to the entire air electrode layer through the current collector. Thereby, the power generation efficiency of the fuel cell can be increased. However, since the current collector is installed so as to cover the fuel electrode and the surface of the air electrode, it does not interfere with the supply of fuel gas and oxidant gas to the fuel electrode and air electrode, and the gas generated at the fuel electrode Should not interfere with the discharge of water. The conductive film in the conductive laminate of the present invention can form a conductive layer on the surface of the fuel electrode or the air electrode, and is excellent in gas permeability. Suitable for use as a current collector in a fuel cell. For this reason, it is possible to obtain a current collector having conductivity and excellent gas permeability by joining the conductive film with the fuel electrode or air electrode of the solid oxide fuel cell as a base.

  FIG. 1 shows an example of a schematic cross section of a solid oxide fuel cell (SOFC) 5 in which a conductive film as a current collector is stacked on a fuel electrode as an inorganic base and an air electrode.

  In the fuel cell 5, a fuel electrode 7 is formed on one side of a solid electrolyte flat plate 6, and an air electrode 8 is formed on the other side. The conductive film 2 is formed on the fuel electrode 7 and the air electrode 8. Are stacked. The conductive film 2 on the fuel electrode 7 and the conductive film 2 on the air electrode 8 are connected to an electric circuit 9. Reference numeral “9” denotes an electric circuit. In FIG. 1, the conductive film 2 is laminated on both the fuel electrode 7 and the air electrode 8, but the conductive film 2 may be laminated only on one of the fuel electrode 7 and the air electrode 8. . Further, the shape of the solid electrolyte is appropriately set and is not limited to a flat plate, and may be, for example, a plate having a curved surface, or a structure such as a cylinder type or a honeycomb type. Also good.

  An electrochemical reactor has the same structure as a solid oxide fuel cell, and has an oxidation electrode on one side and a reduction electrode on the other side with a solid electrolyte in between. The oxidation electrode corresponds to a fuel electrode in a solid oxide fuel cell, and the reduction electrode corresponds to an air electrode in a solid oxide fuel cell. The name of the physical fuel cell has changed. A solid oxide fuel cell is used for power generation, while an electrochemical reactor is used by applying voltage to an oxidation electrode and a reduction electrode by an external power source.

  Electrochemical reactors have been studied for use in purification of diesel exhaust. For example, when an electrochemical reactor is installed in an exhaust gas containing NOX and a solid carbon-based compound and a voltage is applied to the oxidation electrode and the reduction electrode of the electrochemical reactor by an external power source, the oxidation electrode and the reduction electrode The following reactions occur:

Oxidation electrode C + 2O ²⁻ → CO ₂ + 4e ⁻
Reduction electrode 2NO + 4e ⁻ → N ₂ + 2O ²⁻
A current is generated by applying a voltage to the oxidation electrode and the reduction electrode, and electrons (e ⁻ ) generated at the oxidation electrode move to the external power source, and electrons are supplied to the reduction electrode from the external power source. Also, oxygen ions (O ²⁻ ) generated at the reduction electrode permeate the solid electrolyte and move to the oxidation electrode, and are used for the reaction at the oxidation electrode. By this reaction, NOX and solid carbon compounds can be removed from the exhaust gas. The oxidation electrode and the reduction electrode are layers made of a substance that serves as a catalyst for the reaction.

  In the reaction at the oxidation electrode and the reduction electrode, in order to collect electrons generated at the oxidation electrode and distribute the electrons to the entire reduction electrode, a conductor called a current collector or a power distribution body is provided on the surfaces of the oxidation electrode and the reduction electrode. May be placed. The current collector or power distribution body corresponds to a current collector in a solid oxide fuel cell, and has conductivity, as well as an oxidation electrode and a reduction electrode, like the current collector in a solid oxide fuel cell. It must not interfere with the supply of exhaust gas to. The conductive film in the conductive laminate of the present invention can form a conductive layer on the surface of the oxidation electrode or reduction electrode and has excellent gas permeability. Suitable for use as a body or power distribution body. For this reason, a current collector or a power distributor having conductivity and excellent gas permeability can be obtained by bonding the conductive film using the oxidation electrode or the reduction electrode of the electrochemical reactor as a base.

  FIG. 2 shows an example of a schematic cross section of an electrochemical reactor in which a conductive film as a current collector or a current distributor is laminated on an oxidation electrode or a reduction electrode as an inorganic base. The electrochemical reactor 10 has an oxidation electrode 11 formed on one side of a flat plate 6 of solid electrolyte, and a reduction electrode 12 formed on the other side. A conductive film is formed on the oxidation electrode 11 and the reduction electrode 12. 2 are stacked. The conductive film 2 on the oxidation electrode 11 and the conductive film 2 on the reduction electrode 12 are connected to the power supply device 13. In the figure, “13” is a power supply device. In FIG. 2, the conductive film 2 is laminated on both the oxidation electrode 11 and the reduction electrode 12, but the conductive film 2 may be laminated only on one of the oxidation electrode 11 and the reduction electrode 12. . Further, the shape of the solid electrolyte is appropriately set, and is not limited to a flat plate as in the case of the fuel cell, but may be a structure.

  Further, if the conductive film of the conductive laminate formed in the solid oxide fuel cell or electrochemical reactor has a plurality of cracks, the portion where the surface layer of the conductive film becomes a crack is an electrode material, etc. Since the surface to be coated is exposed, gas such as fuel gas or oxygen gas is sent through this part. Therefore, the power generation of the fuel cell is highly efficient while reducing the current collecting resistance and without interfering with the cell reaction. Reactions and reactor redox reactions can be promoted. In addition, the metal in the conductive film is not finely dispersed by becoming a porous body composed of a three-dimensional network skeleton in which the non-cracked portion of the conductive film is branched in a dendritic manner, As a result of the cohesive force, the branches form a large group, and the entire surface area is small, and the metal in the conductive film diffuses due to heat, etc. The phenomenon of entering into is less likely to occur. For this reason, it is possible to suppress the phenomenon of reducing the efficiency of the cell reaction that is likely to occur during the long-time operation of the solid oxide fuel cell or the electrochemical reactor.

  Next, the manufacturing method of an electroconductive laminated body is demonstrated.

  The conductive laminate includes 1) a step of preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent, and 2) applying the slurry composition to an inorganic base to form a coating film. It is manufactured through a step of forming and a step of 3) heating or baking the coating film to eliminate the organic polymer. In addition, a step of drying the coating film to form a dry coating film may be inserted between the steps 2) and 3). By further heating or baking the dried coating film, cracks are likely to occur.

  By heating (baking), only inorganic components that do not disappear by heating (baking) remain, and bubbles and organic polymer disappearance traces remaining in the slurry composition (or dried slurry composition) remain as voids. . For this reason, the conductive film 2 on the inorganic base 3 is a porous body having a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side.

  As the conductive metal particles, the conductive metal particles described above can be used. Among these, silver particles having a purity of 85% or more are preferable. The purity of silver particles is the mass ratio of silver / metal in a metal composed of silver and impurities. Moreover, impurities are metals other than silver, such as copper, palladium, and zinc. The metal and / or alloy preferably has an average particle diameter of 1 to 200 μm (more preferably 10 to 100 μm). When the average particle diameter is within the above range, it is easy to form a porous body having a continuous three-dimensional network skeleton and cracks by heating or firing the slurry composition.

  The organic polymer contained in the slurry composition may be thermoplastic (non-crosslinkable) or thermosetting (crosslinkable). For example, water-soluble polymers such as polyvinyl alcohol, polyacrylamide, starch, and water-soluble celluloses (methyl cellulose: MC, hydroxycellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc.); polyvinyl acetate, acrylic resin, Various thermoplastic / thermosetting synthetic resins such as polyurethane-based, polyester-based, epoxy-resin-based, and fluororesin-based resins, and wood flour, natural fibers, synthetic fibers, and the like can be given.

  In addition, a slurry composition can be prepared by using a synthetic resin emulsion / suspension generally used as a resin binder in the field of water-based paints, or a synthetic resin solution.

  In addition, it is desirable to use the organic polymer containing a high proportion (for example, 70% or more, desirably 75% or more) of an organic polymer having film-forming properties.

  By using such an organic polymer, it becomes easy to form a dry coating film having a uniform coating thickness and good holding of conductive metal particles, and as a result, a conductive film having a uniform thickness can be easily formed. Can get to. Furthermore, it becomes easy to form a crack by heating or baking after drying.

  In the case of a thermoplastic synthetic resin, if it is dissolved in a solvent or heated and melted, it has a film-forming property. However, if it is not dissolved in a solvent or heated and melted, it does not have a film-forming property. Therefore, when water is used as a solvent (which does not cause environmental problems like an organic solvent), the water-soluble polymer is desirable as the organic polymer having film-forming properties.

  In addition, if an uncured synthetic resin (monomer or oligomer) is used as a thermosetting synthetic resin, it has a film-forming property by reaction curing or moisture curing. Does not have membrane properties.

  As the solvent, water is desirable as described above. In addition, organic solvents, alcohol, animal and vegetable oils, and the like may be used. These may be used alone or in combination of two or more.

In addition to the above components, an inorganic binder can also be added to the slurry composition. By adding an inorganic binder, in the process of heating and cooling the slurry composition coated on the inorganic base to obtain a conductive laminate, the inorganic binder is once softened and then cured again, and the conductive film and The inorganic base is firmly bonded (fixed). As the inorganic binder, it is preferable to use an inorganic material that is amorphous and has a glass transition point equal to or lower than the melting point of the conductive metal, and more preferably an inorganic material whose glass transition point is 900 ° C. or lower. If an inorganic binder having a glass transition point equal to or lower than the melting point of the conductive metal is added, the conductive film can be formed by heating the slurry composition at a temperature equal to or higher than the glass transition point of the inorganic binder. For this reason, compared with the case where an inorganic binder is not added, a conductive film can be formed at a low heating temperature. When the glass transition point is 900 ° C. or lower, the conductive film can be formed at a lower heating temperature. As such an inorganic binder, borosilicate glass, zircon frit, SiO ₂ —Al ₂ O ₃ —CaO—Na ₂ O, SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ —CaO—Na ₂ O, SiO _{2 -Al 2 O 3 -B 2 O} 3 -CaO-F 2, etc. _{SiO 2 -Al 2 O 3 -B 2} O 3 -ZrO 2 -F 2 and the like. The content of the inorganic binder is slightly different depending on the characteristics of the conductive metal, but is preferably 1 to 9 parts, more preferably 1 to 5 parts with respect to 100 parts of the conductive metal particles. When the content is too small, an effect on adhesion cannot be expected. Moreover, when there is too much said content, the electroconductivity of an electrically conductive film will be impaired. And if the said content is 1-5 parts with respect to 100 parts of said electroconductive metal particles, the electrically conductive film with the outstanding adhesiveness and the outstanding electroconductivity will be obtained.

  In addition to the above components, additives such as surfactants, wetting agents and antifoaming agents can be added to the slurry composition. The types of additives such as surfactants, wetting agents and antifoaming agents are not particularly limited. They are appropriately selected according to purposes such as stability of properties of the slurry composition and improvement of coating workability, and the addition amount is appropriately set.

  In addition, conditions such as drying / heating temperature and drying / heating / firing time of the coating film (slurry composition) are appropriately set according to the composition of the slurry composition to be used and the composition and shape of the inorganic base. Is. For example, the drying temperature is 10 to 80 ° C., and the heating (firing) temperature is 700 to 1300 ° C.

  Next, a method for forming a conductive laminate having a plurality of cracks in the surface layer of the conductive film will be described.

  In the method for forming the conductive laminate 1 described above, a conductive film having a plurality of cracks 4 can be formed by using a slurry composition having the following composition. In addition,% in the following mixing | blending is a compounding quantity of each compounding when a slurry composition whole quantity is 100%.

Conductive metal particles 35-70% (desirably 45-65%)
Organic polymer 10-25% (preferably 12-20%)
Solvent 15-50% (desirably 20-40%)
Inorganic binder 1-3% (desirably 1.5-2.5%)
Additive 0-3% (desirably 0.3-2.5%)
In order to generate a plurality of cracks in the surface layer of the conductive film of the conductive laminate, the content of each compound in the slurry composition is preferably in the above-described range.

  If the content of the conductive metal is too small, the continuity of the conductive film may be impaired and sufficient conductivity may not be obtained. Further, if the content of the conductive metal is excessive, cracks may not occur.

  If the ratio of the organic polymer having film-forming properties is too small (for example, less than 70%), cracks may not occur. If the content of the organic coating film forming component is excessive, cracks may not occur.

  If the content of the solvent is too small, cracks may not occur. On the other hand, if the content of the solvent is excessive, the continuity of the conductive film is impaired and sufficient conductivity cannot be obtained, and cracks may not occur.

  If the content of the inorganic binder is too small, sufficient adhesion to the inorganic base may not be obtained. On the other hand, if the content of the inorganic binder is excessive, the electric resistance of the conductive film may increase, and sufficient conductivity may not be obtained, and cracks may not occur.

  Hereinafter, the present invention will be described in more detail based on examples.

  In addition, each material used in each Example is as follows.

Inorganic substrate (base material): Ceramic plate formed by firing alumina and zirconia,
Conductive metal particles (Examples 1 and 2) Silver particles having a purity of 93% and an average particle size of 75 μm; (Examples 3 to 18) Silver particles having a purity of 90% and the indicated average particle size,
Inorganic binder: SiO ₂ —Al ₂ O ₃ —CaO—Na ₂ O (Examples 1 and 2), borosilicate glass (Examples 3 to 18)
Additive ... Anionic surfactant <Example 1>
First, a slurry composition having the following composition was prepared. In addition, the ratio of the film-forming organic polymer in the organic polymer of this example is about 64%.

Silver particle 60 parts MC (water-soluble polymer) 9 parts Thermoplastic acrylic resin powder 5 parts Inorganic binder 2 parts Additive 0.5 parts Water (solvent) 20 parts Next, the slurry composition is applied to the surface of the ceramic plate. A coating film having a thickness of about 250 μm was obtained by coating on a portion of 30 mm width × 50 mm length. The coating film was allowed to stand for 24 hours in an environment of a temperature of 20 ° C. and a humidity of 65% and dried (room temperature drying).

  Subsequently, the ceramic plate on which the dried coating film was formed was heated (fired) at 900 ° C. for 10 minutes, and then allowed to stand for 1 hour in an environment at a temperature of 20 ° C. and a humidity of 65%.

  FIG. 3 shows a schematic model diagram of a cross section of the conductive laminate 1 provided with the conductive film 2 on the inorganic base 3 thus prepared.

  The porous body has electrical conductivity, and when observed under a microscope with a magnification of 100 times, the shape of the porous body was a porous body having a continuous three-dimensional network skeleton.

<Example 2>
It is the Example which manufactured the electroconductive laminated body which has a some crack of width 50-200 micrometers in the surface layer of an electrically conductive film. In addition, the ratio of the film-forming organic polymer in the organic polymer of this example is about 78%.

  First, a slurry composition having the following composition was prepared.

Silver particles 60 parts MC (water-soluble polymer) 18 parts Thermoplastic acrylic resin powder 5 parts Inorganic binder 2 parts Surfactant (additive) 0.5 parts Water (solvent) 24.5 parts Next, the slurry composition Was obtained in the same manner as in Example 1 to obtain a ceramic plate having a dry coating film of the slurry composition formed on the surface thereof. Further, after firing in the same manner, the resultant was cooled to room temperature to prepare a conductive laminate.

  And although the dry coating film did not generate | occur | produce the crack in the surface layer, after baking and normal temperature cooling, the surface layer of this porous body has a some crack of width 70-150 micrometers. FIG. 4 shows a schematic cross-sectional model diagram of the cross section of the conductive laminate. And when magnifying 100 times with a microscope, the shape of the porous body was a porous body having a continuous three-dimensional network skeleton. The micrograph is shown in FIG.

<Examples 3 to 18>
Based on the formulation shown in Tables 1 and 2, each slurry composition of Examples 3 to 18 was prepared.

Next, each of the slurry compositions was subjected to a drying step and a firing step under the same conditions as in Example 1 (excluding the thickness of the dried coating film) to prepare a conductive laminate of each Example. The coating thickness has an error within ± 5%.

  Moreover, the electroconductive laminated body which consists of a ceramic board and the electrically conductive film obtained by the said process was made into the test body, and it evaluated by the following test item about each test body.

    1) Presence / absence of cracks: The completed specimen was observed visually to confirm the presence / absence of cracks on the surface layer of the conductive film.

    2) Conductivity: Using a circuit meter (trade name: Hitester 3030-10, manufactured by Hioki Electric Co., Ltd.), the current flow (resistance value) between the two corners that are opposite to the rectangular conductive film It was measured. Set the range selector switch of the circuit meter to “Ω / × 1” and increase the resistance value based on the resistance value when the plus (+) terminal and minus (−) terminal of the circuit meter are in direct contact. Was determined according to the following criteria.

○ ... + 5Ω or less, Δ ... + 5Ω or more, × ... No needle movement 3) Adhesiveness with the substrate: Adhesive tape (adhesive tape manufactured by Nichiban Co., Ltd .: 24mm in width) is applied to the conductive film, Next, after peeling the adhesive tape, the presence or absence of peeling of the electrically conductive film was confirmed.

  Tables 3 and 4 show the evaluation results of the respective specimens. In each Example, it was confirmed that the conductivity was almost equal to or higher than the practical level (Δ). In addition, except for Example 3, it was confirmed that the adhesive had a practical use level.

Model diagram showing the outline of a solid oxide fuel cell Model diagram showing outline of electrochemical reactor Model diagram showing outline of cross section of conductive laminate Model diagram showing an outline of a cross section of a conductive laminate having a plurality of cracks in the surface layer of the conductive film Micrograph of a conductive laminate having multiple cracks on the surface of the conductive film

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive laminated body 2 Conductive film which is a porous body having a continuous three-dimensional network skeleton 3 Inorganic base

Claims (12)

In a conductive laminate including an inorganic base and a conductive film containing a conductive metal,
The conductive film is a porous structure having a film thickness of 10 to 1000 μm directly adhered to the inorganic base,
The porous structure includes a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side ,
The inorganic base is a fuel electrode and / or an air electrode formed on a solid electrolyte in a solid oxide fuel cell, and the conductive film is a current collector.
A conductive laminate characterized by the above.   The conductive laminate according to claim 1, wherein the conductive metal includes one kind or two or more kinds of metals or alloys selected from silver, platinum, and nickel. The conductive laminate according to claim 1 , wherein the conductive film has a plurality of cracks having a width of 10 to 500 μm on a surface layer. A method for producing a conductive laminate according to claim 1 or 2 ,
Preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent; and
Applying the slurry composition to an inorganic substrate to form a coating film;
Heating or baking the coating film to eliminate the organic polymer in the coating film,
The manufacturing method of the electroconductive laminated body characterized by the above-mentioned. A method for producing the conductive laminate according to claim 3 , comprising:
Preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent; and
Applying the slurry composition to an inorganic substrate to form a coating film;
Drying the coating film to obtain a dry coating film;
Heating or baking the dried coating film to eliminate the organic polymer,
A method for producing a conductive laminate, wherein the organic polymer is cracked in the dried coating film as having high coating film forming ability capable of generating cracks during heating or baking. The method for producing a conductive laminate according to claim 4 or 5, wherein the conductive metal particles contain one or more metals and / or alloys selected from silver, platinum, and nickel. . The method for producing a conductive laminate according to claim 6, wherein the conductive metal particles are silver particles having a purity of 85% or more, and an average particle diameter of the silver particles is 1 to 200 μm. The method for producing a conductive laminate according to any one of claims 4 to 7 , wherein the slurry composition further contains an inorganic binder. A slurry composition used for forming a conductive film by applying to an inorganic base to form a coating film, and heating or baking the coating film, the composition comprising:
Conductive metal particles 35-70 mass%,
10-25% by mass of organic polymer,
1-3% by weight of inorganic binder,
0-3 mass% of additive
Solvent 15-50% by mass,
The slurry composition for electrically conductive film formation characterized by these. The said organic polymer contains 70 mass% or more of what has film forming property in this organic polymer, The slurry composition for electrically conductive film formation of Claim 9 characterized by the above-mentioned. In a conductive laminate including an inorganic base and a conductive film containing a conductive metal,
The conductive film is a porous structure having a film thickness of 10 to 1000 μm directly adhered to the inorganic base,
The porous structure is produced by producing a conductive laminate having a continuous three-dimensional network skeleton having voids communicating with the inorganic base from the surface side.
Preparing a slurry composition containing conductive metal particles and an organic polymer dispersed in a solvent; and
Applying the slurry composition to an inorganic substrate to form a coating film;
Heating or baking the coating film to eliminate the organic polymer in the coating film,
The manufacturing method of the electroconductive laminated body characterized by the above-mentioned. The method for producing a conductive laminate according to claim 11, wherein the conductive metal particles contain one or more metals and / or alloys selected from silver, platinum, and nickel.