JP2004127635A - Cell plate for solid oxide fuel cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell plate for a solid oxide fuel cell capable of forming a thin membrane-shaped cell element on a porous substrate having high gas permeability and high mechanical strength and operating at a low temperature, and to provide a method for manufacturing the cell plate. <P>SOLUTION: The porous substrate 2 for supporting the cell element is formed by filling a porous material 4 having gas permeability and electric conductivity in pores or voids 3a of a metallic substrate 3 such as foamed metal or mesh, and cell elements 5, 6 and 7 are formed on the porous substrate 2 by a PVD method, for example. <P>COPYRIGHT: (C)2004,JPO

Description

【００３７】
【発明の効果】
以上説明したように、本発明に係わる固体酸化物形燃料電池用セル板は、電池要素を支持するための多孔質基板として、発泡金属やメッシュのような金属基体の孔や空隙内にガス透過性及び電気伝導性を備えた多孔質材を充填したものを使用しているいるので、金属基体が芯となって支持基板としての強度が確保されると共に、成膜基板としての表面平滑度が確保されることから、電池要素の薄膜形成が容易となると共に、支持基板の薄板化が可能となり、集電体としての電気伝導性、熱伝導性が向上するため、燃料電池用セル板の薄肉化、性能向上と共に、作動温度の低温化、起動時間の短縮が可能になるという極めて優れた効果をもたらすものである。
【００３８】
また、本発明に係わる固体酸化物形燃料電池用セル板の製造方法においては、金属基体の孔や空隙内に多孔質材を形成するに際して湿式めっき法を採用したり、電池要素をスパッタ法や蒸着法などのＰＶＤ法によって成膜したりするようにしているので、比較的低温域で処理することができ、金属基体の酸化による種々の性能劣化を回避することができる。
【００３９】
さらに、本発明に係わる固体酸化物形燃料電池スタックは、本発明よる上記固体酸化物形燃料電池用セル板をインターコネクタを介して積層してなる構成とし、本発明に係わる固体酸化物形燃料電池は、上記固体酸化物形燃料電池スタックを備えたものであるから、小型で高容量、しかも低温作動、高速起動が可能な燃料電池とすることができる。
【図面の簡単な説明】
【図１】（ａ）〜（ｅ）は本発明の第１、第２および第５の実施例に係わる固体酸化物形燃料電池用セル板の製造工程を示す概略断面図である。
【図２】第３の実施例に係わる固体酸化物形燃料電池用セル板の構造を示す概略断面図である。
【図３】第６の実施例に係わる固体酸化物形燃料電池用セル板の構造を示す概略断面図である。
【符号の説明】
１　固体酸化物形燃料電池用セル板
２　基板
３　金属基体
３ａ　孔
４　多孔質材
５　燃料極
６　電解質
７　空気極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid oxide fuel cell (SOFC), in which a thin-film battery element can be formed on a thin film-forming substrate having excellent mechanical strength, and a lower operating temperature and a thinner and smaller size can be obtained. The present invention relates to a battery structure that can be converted.
[0002]
[Prior art]
In a solid oxide fuel cell using a solid electrolyte made of an oxide such as zirconia as an electrolyte, the operating temperature is as high as about 800 to 1100 ° C. Has features. In other words, internal reforming of methane and the like is possible, so that the configuration as a power generation device can be simplified, high efficiency can be achieved by using waste heat, and there is no problem of electrolyte dissipation, so handling is easy. Since carbon can also be used as a fuel, it has features such as being suitable for combination with coal gas. Further, in addition to these features, high-efficiency combined power generation combined with a gas turbine or the like is also expected.
[0003]
On the other hand, as a small power source for a mobile body such as an automobile, various studies have been made on lowering the operating temperature from the viewpoint of ensuring durability against a heat cycle under use conditions with many start-stops.
[0004]
For example, JP-A-4-92369 discloses that a fuel electrode, a ceria-based solid electrolyte having a thickness of 20 μm or less and a porous oxygen electrode are formed on an inorganic porous substrate, and the inorganic porous substrate is used as a current collector. There has been proposed a low-temperature operating solid electrolyte fuel cell in which a void is a fuel gas passage and a void of a porous oxygen electrode is an oxidant gas passage. That is, in the fuel cell, a ceria-based ceramic having a high oxygen ion conductivity is used as the solid electrolyte and the thickness thereof is reduced, and a fuel electrode material is formed on the surface of the inorganic porous substrate to increase the surface area of the fuel electrode. To increase the contact area with the fuel gas, and further increase the contact area with the oxidizing gas using a porous oxygen electrode, thereby reducing the resistance of the solid electrolyte and the resistance of each electrode reaction, thereby reducing the reaction rate. Try to prevent.
[0005]
Further, in Plasma Sprayed Thin-Film for Reduced Operating Temperature, FuelCells Bulletin, pp597-600, 2000, a fuel electrode / electrolyte / air electrode is formed on a porous metal substrate by a thermal spraying method. It is described.
[0006]
[Problems to be solved by the invention]
However, in the low-temperature operating solid electrolyte fuel cell described in JP-A-4-92369, the surface state of the inorganic porous substrate after the formation of the anode material is not dense enough to form the electrolyte. After coating and drying the inorganic material on the inorganic porous substrate on which the anode is formed, the surface of the anode is formed by etching or precision grinding to form a smooth surface where the anode surface is exposed. A solid electrolyte is formed on the substrate. Then, an oxygen electrode material and an organic material are simultaneously deposited on the surface of the solid electrolyte to form a mixed film of these materials, and then a fuel electrode / organic film / solid electrolyte / (oxygen electrode material + organic material) is formed. Since the organic material is removed by heating the inorganic porous substrate to 600 to 1000 ° C., not only the number of steps is increased, but also the porous substrate is heated by removing the organic solvent. Oxidation deteriorates electric conductivity, lowers the function as a current collector, and may cause residual organic components to deteriorate battery characteristics.
[0007]
Further, in the fuel cell described in the above Fuel Cells Bulletin, in order to secure sufficient gas permeability as a porous metal substrate, it is necessary to use a metal sintered body having a rough structure, In order to secure enough strength to withstand, a thick plate must be used, and thinning is hindered.
[0008]
The present invention has been made in view of the above-mentioned problems in a conventional solid oxide fuel cell in which a battery element is supported by a porous substrate functioning as a gas passage and a current collector, and has a gas permeability and a gas permeability. A cell plate for a solid oxide fuel cell capable of forming a thin-film cell element on a porous substrate having excellent mechanical strength and capable of operating at a low temperature, and a method for producing such a cell plate. It is intended to be.
[0009]
[Means for Solving the Problems]
The cell plate for a solid oxide fuel cell according to the present invention fills the pores and / or voids of a metal substrate having a plurality of pores and / or voids with a porous material having gas permeability and electrical conductivity. And the electrolyte is formed on one or both of the fuel electrode and the air electrode on the substrate having the structure described above. It is a means to solve the problem.
[0010]
In the method for manufacturing a cell plate for a solid oxide fuel cell according to the present invention, the porous material filled in the holes and / or voids of the metal substrate can be formed by a wet plating method.
[0011]
Furthermore, the solid oxide fuel cell stack of the present invention has a configuration in which the solid oxide fuel cell cell plates according to the present invention are stacked via an interconnector, and the solid oxide fuel cell of the present invention The solid oxide fuel cell stack according to the present invention is characterized in that the fuel cell stack is provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In a solid oxide fuel cell of the type in which a battery element is formed on a porous substrate, the porous substrate has sufficient strength as a support member for the thin-film battery element and does not lose power generated and output by the battery element without loss. It is necessary to have sufficient electric conductivity for taking out and sufficient gas permeability for supplying fuel gas and oxidizing gas to the battery element.
In the cell plate for a solid oxide fuel cell of the present invention, a metal substrate having a plurality of holes and voids as a porous substrate for supporting a battery element comprising a fuel electrode layer, an electrolyte layer and an air electrode layer, For example, it is formed of a foamed metal, a punching metal, a metal mesh (wire mesh), an expanded metal, a metal nonwoven fabric, etc., and has gas permeability and electric conductivity in its holes (for nonwoven fabrics, voids between metal fibers). A material filled with a porous material is used. That is, the metal substrate serves as a core to secure strength, and the holes and voids of the metal substrate are sealed with a porous material to improve the smoothness of the surface. Not only that, the strength as a supporting substrate is improved and the thickness can be reduced. In addition, the electric resistance as a current collector is reduced and heat conduction is improved. Thus, a simple cell plate can be obtained.
[0013]
In the cell plate for a solid oxide fuel cell of the present invention, it is desirable to use a metal substrate having a plate thickness of 500 μm or less and having holes and voids of 100 μm or less. That is, if the diameter of the hole or the width of the void exceeds 100 μm, the sealing treatment (filling) with a porous material tends to be difficult, and if the thickness exceeds 500 μm, the cell / cell plate becomes smaller due to thinning. It becomes difficult to make.
[0014]
Further, as the porous material for filling the pores and voids of the metal substrate, for example, a porous material such as nickel, nickel cermet, lanthanum cobalt-based oxide, and lanthanum manganese-based oxide can be used. If the size of the micropores or voids in the porous material exceeds 1 μm, it becomes difficult to form a battery element thin film thereon, so that the size is preferably 1 μm or less.
Such a porous material can be formed by a slurry coating method such as a spray method, a screen printing method, or a slip casting method. However, the sealing treatment (filling) can be performed at a low temperature, and the porous material is oxidized. Since the performance degradation due to the deterioration of electrical and thermal conductivity based on is avoided, the wet plating method, for example, the electroless plating method, or the metal and the powder can be simultaneously dispersed by dispersing the functional powder in the electroless plating solution. It is desirable to apply an eutectoid plating method for precipitation.
[0015]
As the electrolyte material in the cell plate for a solid oxide fuel cell of the present invention, known electrolyte materials having oxygen ion conductivity, such as neodymium oxide (Nd ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), Stabilized zirconia in which yttria (Y ₂ O ₃ ), scandium oxide (Sc ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ) and the like are dissolved, ceria (CeO ₂ ) -based solid solution, bismuth oxide solid solution, and LaGa solid solution Lobskite and the like can be suitably used.
The thickness of the electrolyte layer is preferably set to 20 μm or less, since the later-described PVD film formation becomes industrially possible and the internal resistance of the battery is reduced.
[0016]
As the fuel electrode material, nickel, nickel cermet (Ni-SDC or the like), platinum, or the like can be used. Further, as the air electrode material, a lanthanum cobalt-based oxide (such as LSC), a lanthanum manganese-based oxide (such as LSM or LCM), a samarium cobalt oxide (such as SSC), or the like can be used.
When the pores and voids of the metal substrate are filled with a fuel electrode material such as nickel or nickel cermet as a porous material, the porous material can function as a fuel electrode, and a new fuel material can be used. There is no need to form a pole. Similarly, when an air electrode material such as a lanthanum cobalt-based oxide or a lanthanum manganese-based oxide is used as a porous material, it can function as an air electrode, and the film formation of the air electrode is omitted. be able to.
[0017]
The above-mentioned battery elements, that is, the electrolyte, the fuel electrode, and the air electrode are, for example, a sputtering method, a vapor deposition method, an ion plating method, a plasma spraying method, an AD method (aerosol deposition method), a gas deposition method, a laser ablation method, and the like. It is desirable to form a film by a PVD method (physical vapor deposition method), so that a thin-film battery element can be formed at a low temperature and deterioration of battery performance due to oxidation of a metal substrate is avoided. Become.
[0018]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
[0019]
(Example 1)
As shown in FIG. 1 (a), a 0.5 mm thick metal plate having a hole 3a having an average diameter of 50 μm and being a sintered body made of Ni powder is used as the metal substrate 3. 3 was washed with dilute hydrochloric acid and then degreased to remove an oxide film on the surface.
On the other hand, 25 g of nickel sulfate, 20 g of sodium hypophosphite and 10 g of sodium acetate were dissolved in 1 kg of water to prepare a plating solution adjusted to pH 5, which was kept at a constant temperature of 80 ° C.
Then, the metal substrate 3 subjected to the film removal treatment is immersed in the above-mentioned plating solution maintained at 80 ° C. for a predetermined time and subjected to electroless plating, whereby the porous material 4 made of nickel is placed in the holes 3 a of the metal substrate 3. At the same time, a layer made of a porous material 4 having a thickness of 100 μm was formed on the surface of the metal substrate 3 to obtain a substrate 2 as shown in FIG. The average diameter of the fine pores of the porous material 4 was 0.1 μm.
[0020]
Next, the substrate 2 after the electroless plating is washed with water and dried, and a target made of NiO and an SDC (Sm _0.15) are used under a sputtering power of 300 W using argon having a gas pressure of 1 Pa as a sputtering gas. Using a target made of Ce _0.85 O), co-sputtering is performed so that the mass ratio of NiO: SDC becomes 6: 4, and as shown in FIG. A fuel electrode 5 made of nickel and SDC was formed to a thickness of 5 μm.
[0021]
Next, under an argon gas having a gas pressure of 0.2 Pa as a sputtering gas, a YSZ (8 mol% Y ₂ O ₃ —ZrO ₂ ) target was used to form a film by heating at 700 ° C. by a sputtering method with a power of 300 W. As shown in FIG. 1D, an electrolyte 6 made of YSZ was formed on the surface of the fuel electrode 5 to a thickness of 4 μm.
[0022]
Then, as shown in FIG. 1E, a sputtering method using a target made of SSC (Sm _0.8 Sr _0.2 O) under a sputtering power of 300 W using argon of a gas pressure of 1 Pa as a sputtering gas. As shown in the figure, a 10 μm thick air electrode 7 made of SSC was formed on the surface of the electrolyte 6 to obtain a fuel cell plate 1 having a total thickness of about 0.62 mm.
[0023]
(Example 2)
As the metal substrate 3, a stainless steel plate having a thickness of 0.3 mm and having holes 3a having an average diameter of 100 μm formed by photoetching is used. The porous material 4 made of nickel is filled in the holes 3a of the base 3, and a layer made of the porous material 4 having a thickness of 200 μm is formed on the surface of the metal base 3, so that the substrate 2 having a total thickness of 0.5 mm is formed. Got. The average diameter of the fine pores of the porous material 4 was also 0.1 μm.
[0024]
Then, a fuel electrode 5 made of nickel and SDC and having a thickness of 10 μm, an electrolyte 6 made of YSZ having a thickness of 4 μm, and an air electrode made of SSC and having a thickness of 10 μm are formed on the substrate 2 in the same manner as in the above embodiment. 7 was formed in this order to obtain a fuel cell plate 1 having a total thickness of about 0.52 mm having a structure basically similar to that shown in FIG.
[0025]
(Example 3)
As the metal substrate 3, a nickel plate material having a thickness of 0.3 mm and having a hole 3a having an average diameter of 100 μm and formed by photo-etching is used. A metal substrate is immersed for a predetermined time in a processing solution in which SDC powder having a particle size of 0.8 to 1.2 μm is mixed and dispersed in a plating solution, and the processing solution is subjected to electroless eutectoid plating while stirring well. The porous material 4 made of nickel and SDC was filled in the hole 3a of No. 3 to obtain the substrate 2. At this time, the average diameter of the fine pores of the porous material 4 was 0.2 μm.
[0026]
Then, in the same manner as in the first embodiment, a fuel electrode 5 made of nickel and SDC having a thickness of 5 μm, an electrolyte 6 made of YSZ having a thickness of 4 μm, and air having a thickness of 10 μm made of SSC are formed on the substrate 2. By forming the poles 7 in this order, a cell plate 1 for a fuel cell having a total thickness of about 0.32 mm was obtained as shown in FIG.
[0027]
(Example 4)
As the metal substrate 3, a sintered body made of Fe—Cr—Al alloy fiber, a metal plate having a thickness of 0.25 mm having an average gap of 50 μm was used. By applying electroless eutectoid plating, a porous material 4 made of nickel and SDC was filled in the voids of the metal substrate 3 to obtain a substrate 2. The average diameter of the fine pores of the porous material 4 was also 0.2 μm.
[0028]
Then, a fuel electrode 5 made of nickel and SDC having a thickness of 10 μm, an electrolyte 6 made of YSZ having a thickness of 4 μm, and air having a thickness of 10 μm made of SSC are formed on the substrate 2 in the same manner as in the above embodiments. By forming the poles 7 in this order, a fuel cell panel 1 having a total thickness of about 0.27 mm and a structure basically similar to that of FIG. 2 was obtained.
[0029]
(Example 5)
Using a substrate 2 similar to that obtained in Example 2 above, a battery element having the same configuration as that of Example 2 was formed on the substrate 2 by an electron beam evaporation method, and the same as in FIG. The cell plate 1 for a fuel cell having the structure described above was obtained. At this time, the degree of vacuum was 5 × 10 ⁻¹ Pa, and the output power of the electron beam was 300 W.
[0030]
(Example 6)
As the metal substrate 3, a stainless steel plate having a thickness of 0.3 mm and having a hole 3a having an average diameter of 100 μm formed by performing photoetching is used. gave.
[0031]
Then, after pretreatment with an aqueous solution of tin chloride and hydrochloric acid, SSC powder having a particle size of 0.8 to 1.2 μm was dispersed in 80 mL of 0.1 mol / L silver nitrate, 16 mL of 2 mol / L sodium hydroxide, and 2 mol / L ammonia water. The metal substrate 3 is immersed in a plating solution for a predetermined time and subjected to electroless eutectoid plating while stirring well, thereby filling the porous material 4 made of silver and SSC into the holes 3a of the metal substrate 3 and And The average diameter of the fine pores of the porous material 4 was 0.2 μm.
[0032]
Next, after the above-mentioned substrate 2 after eutectoid plating is washed with water and dried, SSC (Sm _0.8 Sr _0.2 O) is used under a sputtering power of 300 W using argon having a gas pressure of 1 Pa as a sputtering gas. An air electrode 7 made of SSC was formed to a thickness of 5 μm on the surface of the substrate 2 by the sputtering method using the above target.
[0033]
Then, under argon at a gas pressure of 0.2 Pa as a sputtering gas, a target formed of YSZ (8 mol% Y ₂ O ₃ —ZrO ₂ ) was used to form a film by heating at 700 ° C. by a sputtering method with a power of 300 W. The electrolyte 6 made of YSZ was formed on the surface of the air electrode 7 to a thickness of 4 μm.
[0034]
Then, NiO: SDC is formed by using a target made of NiO and a target made of SDC (Sm _0.15 Ce _0.85 O) under argon at a gas pressure of 1 Pa as a sputtering gas under a sputtering power of 300 W. By performing co-sputtering at a mass ratio of 6: 4 and forming a fuel electrode 5 made of nickel and SDC to a thickness of 10 μm on the surface of the electrolyte 6, as shown in FIG. Thus, a cell plate 1 for a fuel cell having a total thickness of about 0.32 mm was obtained.
[0035]
The specifications of each cell plate 1 for fuel cells obtained by the above examples are summarized in a table. In any of the embodiments, it is possible to stably form the battery elements 5, 6, and 7 on the thin film-forming substrate 2 in a thin film form, and to obtain the fuel cell panel 1 having a small thickness. confirmed. The cell plate 1 for a solid oxide fuel cell having such a structure can be laminated via an interconnector and incorporated into a fuel cell as a stack, and is small in size, high in performance, and particularly capable of operating at low temperatures and high speed. A solid oxide fuel cell that can be started can be obtained.
[0036]
[Table 1]

[0037]
【The invention's effect】
As described above, the cell plate for a solid oxide fuel cell according to the present invention, as a porous substrate for supporting a cell element, has a gas permeation into a hole or a void of a metal base such as a foamed metal or a mesh. Is filled with a porous material having electrical and electrical conductivity, so that the metal substrate serves as a core, ensuring the strength as a support substrate and the surface smoothness as a film-forming substrate. As a result, the thin film of the cell element can be easily formed, and the thickness of the support substrate can be reduced, and the electric conductivity and heat conductivity of the current collector can be improved. This has an extremely excellent effect that the operating temperature can be lowered and the start-up time can be shortened as well as the performance and the performance are improved.
[0038]
Further, in the method for manufacturing a cell plate for a solid oxide fuel cell according to the present invention, a wet plating method is used when forming a porous material in holes or voids of a metal substrate, or a cell element is formed by a sputtering method or the like. Since the film is formed by a PVD method such as a vapor deposition method, the film can be processed in a relatively low temperature range, and various performance deteriorations due to oxidation of the metal substrate can be avoided.
[0039]
Furthermore, the solid oxide fuel cell stack according to the present invention has a configuration in which the above-described cell plates for a solid oxide fuel cell according to the present invention are laminated via an interconnector, and the solid oxide fuel cell according to the present invention Since the battery is provided with the solid oxide fuel cell stack, it can be a small, high-capacity fuel cell capable of operating at low temperatures and starting at high speed.
[Brief description of the drawings]
1 (a) to 1 (e) are schematic cross-sectional views showing steps for manufacturing a cell plate for a solid oxide fuel cell according to first, second and fifth embodiments of the present invention.
FIG. 2 is a schematic sectional view showing the structure of a cell plate for a solid oxide fuel cell according to a third embodiment.
FIG. 3 is a schematic sectional view showing the structure of a cell plate for a solid oxide fuel cell according to a sixth embodiment.
[Explanation of symbols]
Reference Signs List 1 Cell plate for solid oxide fuel cell 2 Substrate 3 Metal substrate 3a Hole 4 Porous material 5 Fuel electrode 6 Electrolyte 7 Air electrode

Claims (11)

At least one of a fuel electrode and an air electrode is provided on a substrate in which a plurality of holes and / or voids are filled with a porous material having gas permeability and electric conductivity in the holes and / or voids of the metal substrate. And a solid oxide fuel cell. 2. The cell plate for a solid oxide fuel cell according to claim 1, wherein the metal substrate has a plate thickness of 500 μm or less having holes and / or voids of 100 μm or less. 3. The cell plate for a solid oxide fuel cell according to claim 1, wherein the porous material has micropores and / or voids of 1 μm or less. 4. The cell plate for a solid oxide fuel cell according to any one of claims 1 to 3, wherein the electrolyte is formed to a thickness of 20 µm or less. The cell plate for a solid oxide fuel cell according to any one of claims 1 to 4, wherein a fuel electrode and an air electrode are formed on the substrate so as to sandwich an electrolyte. The cell plate for a solid oxide fuel cell according to any one of claims 1 to 4, wherein the porous material comprises a fuel electrode material. The cell plate for a solid oxide fuel cell according to any one of claims 1 to 4, wherein the porous material is made of an air electrode material. The solid material for a solid oxide fuel cell according to any one of claims 1 to 7, wherein the porous material filled in the holes and / or voids of the metal substrate is formed by a wet plating method. Board manufacturing method. The method for manufacturing a cell plate for a solid oxide fuel cell according to claim 8, wherein the electrode and the electrolyte on the substrate are formed by a PVD method. A solid oxide fuel cell stack comprising the solid oxide fuel cell cell plates according to any one of claims 1 to 7 laminated via an interconnector. A solid oxide fuel cell comprising the solid oxide fuel cell stack according to claim 10.

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