JP2000182628A - Manufacture of porous electrode for thin film solid electrolyte element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode with excellent air permeability by applying an electrode material composed of a carbon or a carbon compound and of a metal compound decomposable at a temperature lower than that which a carbon or a carbon compound is oxidized and gasified onto a substrate and by heating at least at a temperature that a carbon or a carbon compound is gasified. SOLUTION: In this manufacturing method, a platinum rhodinate as a metallic compound 14 and a graphite fine powder as a carbon fine powder 15 are mixed and an electrode material paste 13 containing a diluent is applied onto a porous substrate 11. The substrate 11 is heated at 900 deg.C and the platinum rhodinate is decomposed to form a thin film of a platinum particle 16 and the graphite fine powder 15. The graphite fine powder 15 is consumed at 700 to 900 deg.C and a porous thin film 12 having an air hole 17 is formed. The metallic compound 14 is an organic metallic salt of noble metal such as gold or silver or of rhodinate, etc., or an inorganic metallic salt of halide, etc.; a platinum chloride such as hexachloroplatinic acid hexahydrate is preferable. 1 to 5 pts.wt. of the carbon fine powder to 100 pts.wt. of the metallic compound is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a porous electrode used for a sensor element using a solid electrolyte thin film.

[0002]

2. Description of the Related Art As an example of a thin-film solid electrolyte device using a porous electrode, there is an oxygen separator for preventing the oxidation of food (for example, Japanese Patent Application Laid-Open No. 9-241003). FIG. 6 shows the configuration of this oxygen separator. Using zirconia as a solid electrolyte, a first platinum electrode 2, a zirconia thin film 3, and a second platinum electrode 4 are sequentially laminated on a porous substrate 1 made of alumina. The first electrode 2 and the second electrode 4 are connected to a DC power supply 5. Next, the operation of the oxygen separator will be described. The oxygen separator having the above-described configuration is arranged such that the porous substrate 1 side is placed in a closed container 6 such as a food storage, and the second platinum electrode 4 side is placed on the atmosphere side. When a negative voltage is applied to the first platinum electrode 2 and a positive voltage is applied to the second platinum electrode 4,
The oxygen gas in the food storage 6 receives electrons at the first platinum electrode 2 and becomes oxygen ions having a negative potential. Since the zirconia thin film 3 has oxygen ion conductivity, the oxygen ions move from the first electrode 2 to the second electrode 4, and emit electrons at the second electrode 4 to form oxygen ions. Released as gas into the atmosphere. In this way, the food storage can be kept in a deoxygenated atmosphere, so that the food in the storage is prevented from deteriorating and the food can be stored for a long time.

[0003] It is necessary to use a porous material as an electrode of such an oxygen separator so that oxygen gas can pass therethrough. Conventionally, the first and second electrodes are formed by a sputtering method, and by controlling sputtering conditions such as adjusting the degree of vacuum, the electrodes are formed to be a porous body in which platinum fine particles are aggregated. .

As another example of a solid electrolyte thin film element using a porous electrode, there is a humidity sensor (for example, Japanese Patent Application Laid-Open No. 10-82751). This humidity sensor uses barium-cerium-gadolinium oxide as a solid electrolyte, and is configured by sequentially laminating a first electrode, a solid electrolyte thin film, and a second electrode on a silicon substrate. The first electrode and the second electrode are connected to an AC signal source that applies an AC voltage, and are connected to a measurement circuit that can measure the impedance of the sensor element. In the barium-cerium-gadolinium oxide thin film, hydrogen ions taken from water existing as water vapor in the air exist, and the amount of the hydrogen ions depends on humidity. Therefore, humidity can be obtained by measuring electrical characteristics such as impedance of the oxide thin film. Further, the sensor having such a configuration functions as a sensor not only for humidity but also for a gas containing hydrogen such as a hydrocarbon gas.

In such a sensor, since moisture in the atmosphere passes through the second electrode and hydrogen ions are taken into the oxide thin film, it is necessary to use an electrode having excellent air permeability.
Conventionally, the responsiveness of a humidity sensor has been improved by providing slit-shaped holes in a metal thin film formed by a sputtering method.

In order to produce a porous electrode, in addition to using the above-described sputtering method, a paste containing a metal compound is applied to a base and fired to form a metal thin film.
There are a method of forming holes in this thin film, a method of applying a paste in which metal particles having a particle size of about 1 μm are dispersed on a base, and baking to form a porous thin film. There is also a method of forming a metal thin film using a mask patterned in a slit shape.

[0007]

As described above, the characteristics of the oxygen separator and the humidity sensor are determined by the ventilation speed of the electrodes. Therefore, it is important to produce an electrode having excellent air permeability. Since a porous electrode produced by a conventional sputtering method is an aggregate in which fine particles are densely bonded, there is a limit in providing sufficient air permeability.
In addition, in order to form slit-shaped holes or the like in a metal thin film formed by a sputtering method or the like, it is necessary to etch the thin film by a photolithography method or an ion milling method after forming the film, which complicates the manufacturing process. There was a problem.

Further, when a porous electrode is formed using a paste containing metal particles having a particle size of about 1 μm, the contact area with a base is small and the adhesion is poor, so that a thin-film solid electrolyte element having excellent performance is provided. Cannot be manufactured. In the method using a patterned mask, the area of a hole to be formed is large,
There is a problem that the surface area of the solid electrolyte cannot be used effectively. In view of the above problems, an object of the present invention is to provide a method for easily producing a porous electrode which is excellent in air permeability and can produce a high-performance thin-film solid electrolyte element.

[0009]

A method of manufacturing a porous electrode for a thin film solid electrolyte device according to the present invention comprises the steps of sequentially forming a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode. A method for producing a metal electrode of a thin-film solid electrolyte device constituted by laminating, comprising a step of applying and heating an electrode material on a base, wherein the electrode material is carbon or a carbon compound, and the carbon or carbon compound. And a metal compound that can be decomposed at a temperature lower than the temperature at which the carbon or the carbon compound is oxidized and gasified, and wherein the heating is performed at a temperature equal to or higher than the temperature at which the carbon or the carbon compound is oxidized and gasified. Here, it is preferable to use platinum chloride as the metal compound. Further, another method for producing a porous electrode for a thin-film solid electrolyte element of the present invention includes a step of applying and heating an electrode material on a base, and prior to the step of applying the electrode material, a step of applying carbon to the surface of the base. Alternatively, the method may further include a step of spraying a powder of a carbon compound, and in the heating step, heating is performed at a temperature equal to or higher than a temperature at which the carbon or the carbon compound is oxidized and gasified.

Further, another method of manufacturing a porous electrode for a thin-film solid electrolyte device according to the present invention includes a step of forming a metal thin film on a base, and a step of heating to make the metal thin film porous. Features. Another method for producing a porous electrode for a thin-film solid electrolyte element according to the present invention includes a step of forming a metal thin film on a base, a step of applying a paste in which metal powder having a particle size of 0.1 to 10 μm is dispersed, and a heating step. Then, a step of making the metal thin film porous and firing the paste is provided. The method for producing a porous electrode for a thin-film solid electrolyte device according to the present invention further comprises:
A step of applying and drying a first paste in which 1 μm metal powder is dispersed, a step of applying a second paste in which metal powder having a particle size of 1 to 10 μm is dispersed, and heating the first and second pastes. A step of firing the second paste.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Since the porous electrode for a solid electrolyte thin film element is a metal porous thin film, the following embodiment of the present invention will be described as a method for manufacturing the porous thin film. Embodiment 1 In this embodiment, a porous thin film is manufactured by applying and firing an electrode material paste containing a metal compound and carbon or a carbon compound on a porous substrate or a solid electrolyte thin film. An embodiment of the present invention will be described with reference to FIG. First, as shown in FIG. 1A, an electrode material paste 1 in which carbon or a fine powder 15 of a carbon compound is mixed with a metal compound 14 and a diluent is added as necessary.
3 is applied on the porous substrate 11. Next, the substrate is heated to a temperature at which the fine powder 15 is oxidized and gasified (hereinafter, referred to as burned out).

For example, when platinum rosinate in which platinum and rosin are bonded to the metal compound 14 and graphite fine powder having a particle diameter of 66 nm is used as the carbon fine particles 15, when the substrate is heated at 900 ° C. 350-4
At 00 ° C., the platinum rosinate decomposes to form a thin film composed of platinum particles 16 and graphite fine powder 15 (FIG. 1).
(B)) Subsequently, at about 700 to 900 ° C., the graphite fine powder 15 is burned off, and the porous thin film 12 having the air holes 17 is formed. Although the obtained porous thin film 12 is a thin film in which metal particles 16 having a particle size of about 0.1 μm are bonded very densely, the pores 17 are formed after the carbon or carbon compound is removed. It becomes a porous body having very excellent air permeability. Therefore, when this porous thin film is used for the first or second electrode, a thin film solid electrolyte element having excellent characteristics can be manufactured. In addition, since the obtained porous thin film has small surface irregularities and excellent smoothness, it is particularly preferable to use it for the first electrode.

If the compounding amount of carbon or the carbon compound with respect to the metal compound in the electrode material paste is too large, the metal cannot form a porous thin film, resulting in an island-like structure. Even if it can be formed, since the density of the metal particles is low, the adhesive force between the metal fine particles and between the metal fine particles and the base is weakened, and the metal particles are easily separated. Conversely, if the amount of carbon or the carbon compound is too small relative to the metal compound in the electrode material paste, a porous thin film having sufficient air permeability cannot be obtained. For example, it is suitable to mix about 1 to 5 parts by weight of graphite fine powder with respect to 100 parts by weight of platinum rosinate. Further, by adjusting the amount of carbon or a carbon compound, the porosity of the obtained porous thin film can be adjusted to a desired value.

It is suitable to use a noble metal such as gold, silver, palladium or platinum as the metal constituting the electrode. As the metal compound, any compound can be used as long as it decomposes at a temperature lower than the temperature at which the carbon or the carbon compound to be mixed is burned off. For example, rosinates in which a metal atom is bonded to rosin, resinates in which a metal atom is bonded to a resin, organometallic compounds such as metal oxalates, metal naphthenates, and metal mercaptans, and inorganic halides such as metal halides and sulfides A metal compound is used. In particular, it is preferable to use a platinum chloride such as hexachloroplatinic acid hexahydrate because a porous electrode can be manufactured at lower cost than using a special organometallic compound.

As the carbon or carbon compound to be mixed with the electrode material paste, any carbon or carbon compound can be used as long as it burns at a temperature higher than the decomposition temperature of the metal compound. For example, fine powder of graphite or fine powder of a high molecular weight hydrocarbon compound such as polyethylene or polystyrene may be used. Further, it may be a liquid having a relatively large molecular weight such as polyethylene glycol.

<Embodiment 2> In the embodiment of the present invention, the fine powder of carbon or carbon compound mixed with the electrode material paste in the embodiment 1 is uniformly applied to the base surface before the electrode material paste is applied. After spraying, a paste of a metal compound is applied and fired to produce a porous thin film. This embodiment will be described with reference to FIG. First, fine powder 25 of carbon or a carbon compound is sprayed on the surface of the solid electrolyte thin film 23. The sprayed fine powder partially aggregates as shown in FIG. 2A, and firmly adheres to the surface of the solid electrolyte thin film 23 by static electricity.
It is preferable that the layer of the fine powder has the same thickness as that of the electrode to be formed. Then, the paste 26 of the metal compound is printed to fill the voids of the fine powder 25 with the paste 26 (FIG. 2).
(B)) Then, the substrate is heated to a temperature at which the fine powder 25 is burned off, and a porous thin film 27 to which the metal particles 24 are bonded is formed in the same manner as in the first embodiment (FIG. 2C). .

According to the present embodiment, unlike the first embodiment, there is no need to mix carbon or a carbon compound and a metal compound, so that there is an advantage that the operation is easy. This is particularly effective when the two are not mixed even if they are to be mixed.

Embodiment 3 In this embodiment, a thin metal film is formed by a sputtering method or a method of applying and sintering a paste containing a metal compound (hereinafter referred to as a coating sintering method). By subjecting this to a heat treatment, the metal thin film is made porous to produce a porous thin film. This embodiment will be described with reference to FIG. A metal thin film 32a having a thickness of about 0.2 μm and having no air permeability is formed on the porous substrate 31 having the holes 33 by a sputtering method or the like. Next, the substrate is heated.
For example, when the metal thin film is made of platinum, 700 to 90
When the substrate is heated at 0 ° C., the bonds between the platinum atoms are weakened and the platinum atoms move easily along the substrate surface. Then, since the surface tension acts on the softened metal thin film, a vent 34 is formed in the metal thin film 32a, and a porous thin film 32b as shown in FIG. 3B is formed.

According to the present embodiment, a porous thin film having air permeability can be manufactured only by performing a heat treatment after forming a metal thin film, so that the manufacturing is easy. Further, this embodiment is applicable not only to the first electrode but also to the manufacture of the second electrode. When the metal thin film is formed of gold, silver, or the like, heating at a temperature of about 500 to 900 ° C. can make the metal thin film porous. The thickness of the metal thin film to be formed is 0.1 to 0.5 μm
When it is about m, the ventilation hole 34 having an appropriate size may be formed. When the metal thin film is formed by the coating and sintering method, for example, using the platinum rosinate described in the first embodiment, the metal thin film is formed by firing at 350 to 400 ° C. By performing the heat treatment at 900 ° C., the porous thin film 32 b having the vent holes 34 is formed.
Can be formed.

Embodiment 4 In this embodiment, after a metal thin film is formed by a sputtering method, a paste containing metal particles having a particle size of about 0.1 to 10 μm is applied to the thin film and subjected to heat treatment. Thereby, the paste is fired and the metal thin film is made porous to produce a porous thin film. This embodiment will be described with reference to FIG. As shown in FIG. 4A, the solid electrolyte thin film 43 has a thickness of 0.2 in the same manner as in the third embodiment.
A metal thin film 44a of about .mu.m is formed, and a
Paste 4 in which metal particles 46 of about 1 to 10 μm are dispersed
5 is applied. Then, the substrate is subjected to a heat treatment. For example, a metal thin film is formed of platinum, and the metal particles have a particle diameter of 1 μm.
When platinum particles of the order of magnitude are used, when heat treatment is performed at 900 ° C., as shown in FIG. 4 (b), the platinum particles 46 are bonded, and a ventilation 47 is formed in the metal thin film 44a to form a porous thin film 44b. Become. At the same time, the platinum particles 46
And the porous thin film 44b are strongly bonded.

According to the present embodiment, the obtained porous thin film has high air permeability and high adhesion between the solid electrolyte thin film 43 and the metal thin film 44b. Therefore, when this porous thin film is used for an electrode, the characteristics of the obtained thin film solid electrolyte element are more improved than when a conventional porous thin film formed using only a paste containing metal particles having a particle size of about 1 μm is used for an electrode. improves. To obtain a porous film with excellent air permeability,
The diameter of the metal particles is preferably 0.1 to 10 μm, and the thickness of the metal thin film 44a is preferably about 0.1 to 0.5 μm.
Further, the metal forming the metal thin film and the metal particles in the paste need not necessarily be the same kind of metal, and may be a combination of different metals.

Embodiment 5 In this embodiment, a first paste containing fine metal particles having a particle size of about 0.1 to 1 μm is applied and dried, and then a first paste having a particle size of about 1 to 10 μm is formed. A second paste containing metal particles is applied and heat-treated to produce a porous thin film. This embodiment will be described with reference to FIG. First, as shown in FIG. 5A, a particle diameter of 0.1 μm is formed on the solid electrolyte thin film 53.
After applying and drying a first paste 55 in which metal particles 54 of about m are dispersed, metal particles 57 having a particle diameter of about 1 μm are applied.
Is applied and a second paste 56 is dispersed. Next, the substrate is subjected to a heat treatment to bake the first and second pastes.

For example, when platinum particles are used as the metal particles, when heat treatment is performed at 900 ° C., as shown in FIG. 5B, a layer 58 in which fine metal particles 54 are closely bonded and a metal particle 57 are bonded. Thus, a porous thin film composed of the layer 59 is obtained. The obtained porous thin film has high air permeability, and the area of the contact portion between the solid electrolyte thin film 53 and the platinum particles 54 is large. Therefore, when this porous thin film is used for an electrode, the characteristics of the obtained thin film solid electrolyte element are more improved than when a conventional porous thin film formed using only a paste containing metal particles having a particle size of about 1 μm is used for an electrode. improves. In order to obtain a porous thin film having excellent air permeability, the thickness of the layer 58 should be 0.2 to 0.2.
The thickness is preferably about 1 μm. Note that the metal particles 54 and the metal particles 57 may be a combination of different types of metals.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the production of a porous thin film used for a porous electrode of the oxygen separator shown in FIG. 6 as an example. << Example 1 >> By the method described in Embodiment 1, FIG.
A porous thin film shown in (c) was produced. Platinum rosinate was used as the metal compound 14, and graphite fine powder having a particle size of 66 nm was used as the fine carbon powder 15. First, 1 gram of the graphite fine powder was mixed with 5 cc of toluene to prepare a graphite paste. Next, platinum rosinate and graphite paste were added in a weight ratio of 10%.
The electrode material paste 13 was produced by mixing at a ratio of 0: 7. The electrode material paste 13 thus produced was printed on the alumina substrate 11 by a screen printing method (FIG. 1A). Subsequently, the substrate was baked at 700 ° C. for 10 minutes. As a result, a porous thin film 12 was obtained in which appropriate ventilation holes 17 were formed in a metal particle layer in which platinum particles 16 of about 0.1 μm were densely gathered (FIG. 1C). Also,
The surface of the obtained porous thin film is excellent in smoothness, and when this porous thin film is used for the first electrode, a solid electrolyte thin film or a second electrode can be successfully produced thereafter, and excellent performance is obtained. Was manufactured.

When the amount of graphite mixed with platinum rosinate was changed and the state of formation of the porous thin film was examined, when 20 parts by weight or more of graphite paste was mixed with 100 parts by weight of platinum rosinate, platinum fine particles were reduced. It was not possible to form a porous thin film by agglomerating in an island shape. Further, the adhesion between the platinum fine particles and the underlying porous substrate was weakened, and the particles were easily peeled off. Conversely, graphite paste was added in an amount of 0.1 part by weight with respect to 100 parts by weight of platinum rosinate.
When the amount was less than 5 parts by weight, a porous electrode having sufficient air permeability could not be obtained.

Example 2 As the metal compound 14, inexpensive hexachloroplatinic acid hexahydrate was used. First, 5 g of hexachloroplatinic acid hexahydrate was dissolved in 19 cc of ethylene glycol. The obtained solution and graphite fine powder having a particle diameter of 66 nm were mixed at a weight ratio of 100: 1 to prepare an electrode material paste. Except that this electrode material paste was used, a porous thin film was produced in the same manner as in Example 1, and a material having excellent air permeability was obtained.

Example 3 A porous thin film shown in FIG. 2C was manufactured by the method described in the second embodiment. First, a zirconia thin film 23 was formed on the porous substrate on which the first electrode was formed by a sputtering method. On the surface of the zirconia thin film 23, the same graphite fine powder 25 as in Example 1 was uniformly dispersed. The graphite fine powder 25 was firmly adsorbed on the zirconia thin film 23 by static electricity. After printing a paste obtained by diluting platinum rosinate with toluene on the fine powder 25 (FIG. 2).
(B)) By baking at about 700 ° C. to form a porous thin film (FIG. 2 (c)), as in Example 1, despite being a layer of dense metal particles, the air permeability was low. An excellent porous thin film was obtained. << Example 4 >> By the method described in Embodiment 3, FIG.
The porous thin film shown in (b) was manufactured. First, a platinum thin film 32a having a thickness of 200 nm was formed on a porous substrate 31 made of alumina by a sputtering method (FIG. 3).
(A)). The sputtering conditions were the same as those for forming a normal dense thin film. Then, the substrate was placed in a heating furnace and heated at 700 to 900 ° C. as a result,
As shown in FIG. 3B, the platinum thin film 32a became a porous thin film 32b in which countless vent holes 34 were formed, and was excellent in air permeability.

Example 5 The porous thin film shown in FIG. 4B was manufactured by the method described in the fourth embodiment. First, a zirconia thin film 43 was formed on the porous substrate on which the first electrode was formed by a sputtering method. On the surface of the zirconia thin film 43, a platinum thin film 44a having a thickness of 50 nm was formed by a sputtering method. Next, platinum particles 46 having a particle size of about 1 μm are formed on the platinum thin film 44a.
Is dispersed and paste 45 (manufactured by Tanaka Kikinzoku Co., Ltd., product number TR-7905) is applied by printing (FIG. 4).
(A)). Then, put the substrate in a heating furnace,
For 30 minutes. As a result, as shown in FIG. 4B, a porous thin film was formed on the zirconia thin film 43, in which a platinum thin film 44b having an air hole 47 and a layer composed of platinum particles 46 were bonded. Also, the adhesion between the platinum thin film 44b and the zirconia thin film 43 was excellent. When this porous thin film was used for the second electrode, it was possible to produce an oxygen separator having better performance than before.

Example 6 A porous thin film shown in FIG. 5B was manufactured by the method described in the fifth embodiment. First, a zirconia thin film 53 was formed on the porous substrate on which the first electrode was formed by a sputtering method. On the surface of the zirconia thin film 53, a paste 55 in which platinum particles 54 having a particle diameter of about 0.1 μm and separated from the paste used in Example 5 were dispersed was applied by printing. The substrate was placed in a heating furnace, heated at 900 ° C. for 30 minutes, and dried. Next, the substrate was taken out of the heating furnace, cooled to room temperature, and then the same paste 56 used in Example 5 was printed on the previously dried paste 55. Then, the substrate was placed in a heating furnace and baked at 900 ° C. for 30 minutes. As a result, as shown in FIG. 5B, on the zirconia thin film 53, a porous thin film composed of a layer 58 to which platinum fine particles 54 were bonded and a layer 59 to which platinum particles 57 were bonded was obtained. This porous thin film was excellent in air permeability, and had a large contact area between the platinum fine particles 54 and the zirconia thin film 43. When this porous thin film was used for the second electrode, it was possible to produce an oxygen separator having better performance than before.

[0030]

As described above, according to the present invention, a porous electrode which is excellent in air permeability and can produce a high performance thin film solid electrolyte element can be formed by a simple process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a step of manufacturing a porous electrode according to Embodiment 1 of the present invention.

FIG. 2 is a schematic cross-sectional view showing a step of manufacturing a porous electrode according to Embodiment 2 of the present invention.

FIG. 3 is a schematic cross-sectional view showing a step of manufacturing a porous electrode according to Embodiment 3 of the present invention.

FIG. 4 is a schematic cross-sectional view showing a step of manufacturing a porous electrode according to Embodiment 4 of the present invention.

FIG. 5 is a schematic cross-sectional view showing a step of manufacturing a porous electrode according to Embodiment 5 of the present invention.

FIG. 6 is a longitudinal sectional view of a main part of the oxygen separation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Porous substrate 12 Porous thin film 13 Electrode material paste 14 Metal compound 15 Fine powder, such as graphite 16 Metal particles 17 Vent

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 4/92 H01M 4/92 5H026 8/02 8/02 E 8/12 8/12 // A23L 3 / 3436 A23L 3/3436 C01B 13/02 C01B 13/02 ZF term (reference) 2G046 AA09 AA18 BA01 BA09 BB04 BC05 EA02 EA07 EA09 FB00 FE00 FE02 FE29 FE31 2G060 AA01 AB02 AF06 AG15 BA01 BB09 A044B02A04 MC04 BC06 5H018 AA06 AS03 BB01 BB08 BB12 BB17 EE03 EE06 EE08 HH01 HH08 5H026 AA06 BB00 BB01 BB04 BB08 BB10 EE02 EE05 EE06 HH01 HH08

Claims (8)

[Claims] 1. A method for manufacturing a metal electrode of a thin-film solid electrolyte element, comprising: sequentially stacking a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode, Including a step of applying and heating an electrode material on a substrate, wherein the electrode material includes carbon or a carbon compound and a metal compound that can be decomposed at a temperature lower than a temperature at which the carbon or the carbon compound is oxidized and gasified. And heating at a temperature at which the carbon or carbon compound is oxidized and gasified or higher in the heating step. 2. The method according to claim 1, wherein platinum chloride is used as the metal compound. 3. A method for manufacturing a metal electrode of a thin-film solid electrolyte element, comprising: sequentially stacking a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode, The step of applying and heating an electrode material on a base, and the step of applying a powder of carbon or a carbon compound to the surface of the base prior to the step of applying the electrode material, further comprising the step of: Alternatively, a method for producing a porous electrode for a thin-film solid electrolyte device, comprising heating at a temperature higher than a temperature at which a carbon compound is oxidized and gasified. 4. The method for producing a porous electrode for a thin-film solid electrolyte device according to claim 1, wherein graphite is used as said carbon. 5. The method for producing a porous electrode for a thin-film solid electrolyte device according to claim 1, wherein a polymer compound is used as the carbon compound. 6. A method for manufacturing a metal electrode of a thin-film solid electrolyte element, comprising: sequentially stacking a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode, A method for producing a porous electrode for a thin-film solid electrolyte element, comprising: a step of forming a metal thin film on an underlayer; and a step of heating the metal thin film to make it porous. 7. A method for manufacturing a metal electrode of a thin-film solid electrolyte element, comprising: sequentially stacking a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode, Forming a metal thin film on the lower surface, applying a paste in which metal powder having a particle size of 0.1 to 10 μm is dispersed, and heating to make the metal thin film porous and bake the paste. A method for producing a porous electrode for a thin-film solid electrolyte device, comprising: 8. A method for producing a metal electrode of a thin-film solid electrolyte device, comprising: sequentially stacking a porous substrate, a first metal electrode, a solid electrolyte thin film, and a second metal electrode, A step of applying and drying a first paste in which metal powder having a particle size of 0.1 to 1 μm is dispersed and a step of applying a second paste in which metal powder having a particle size of 1 to 10 μm is dispersed, And a step of heating and baking the first and second pastes. A method for producing a porous electrode for a thin-film solid electrolyte device, comprising the steps of: