JP2014069989A - Oxygen ion conductor, and electrochemical device obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen ion conductor having high density and high oxygen ion conductivity and an electrochemical device obtained by using the oxygen ion conductor.SOLUTION: The oxygen ion conductor comprises: an ion conduction part in which at least one of calcium oxide, gadolinium oxide and rare earth metal oxide is contained as a stabilizer and which is based on zirconium oxide; and an electron conduction part based on lanthanum chromite-based perovskite-type oxide. The oxygen ion conductor has the zirconium oxide content higher than the content of the lanthanum chromite-based perovskite-type oxide.

Description

  The present invention relates to an oxygen ion conductor having oxygen ion conductivity and an electrochemical device using the same.

  Oxygen ion conductors used in electrochemical devices for decomposing methane gas, etc. are generally composed of a dense film whose main component is a component having a perovskite structure, which is dissociated from an oxygen-containing gas and ionized. It is required to produce high-purity oxygen by moving the oxygen ions thus formed from the front side to the back side of the membrane so that they exist in the state of ions or are recombined. In particular, when the oxygen ion conductor has electron conductivity in addition to oxygen ion conductivity, the electrons move in the direction opposite to the direction of oxygen ion movement, so the front and back surfaces are electrically connected. There is an advantage that it is not necessary to provide an external electrode, an external circuit, or the like for connecting electrons to and returning electrons from the back side to the front side.

For example, Patent Document 1 includes a layered structure including a dense layer for transporting oxygen ions and electrons and a porous support layer that mechanically supports the layered structure, and the dense layer includes a mixed conductor, an ion It is formed of a conductor and a mixture containing a metal, and the mixed conductor and the ionic conductor are present in the mixture in an amount capable of conducting oxygen ions through the dense layer, and the mixed conductor and the metal conduct electronic through the dense layer in the mixture. Proposed oxygen ion transport composite element in which porous support layer is formed of oxide dispersion strengthened metal, metal reinforced intermetallic alloy, boron doped Mo ₅ Si ₃ based intermetallic alloy or a combination thereof Has been.

The mixed conductor is La _0.2 Sr _0.8 Fe _0.6 Ti _0.4 O ₃ or La _0.2 Sr _0.8 Fe _0.8 Cr _0.2 O _3. The ion conductor is gadolinium doped ceria, samarium doped ceria, yttria stabilized zirconia, ceria, zirconia, scandium stabilized zirconia, lanthanum, strontium, gallium, magnesium oxide, or the formula MBiOx (M is yttria, molybdenum or tungsten). It is disclosed that it is a doped bismuth oxide represented by

Special Table 2007-527468

  However, the dense layer constituting the oxygen ion transport composite element proposed in Patent Document 1 cannot be said to have a sufficiently high density, and there is a problem that the oxygen ion conductivity cannot be sufficiently increased. .

  In view of such problems, the present invention provides an oxygen ion conductor having a sufficiently high density and high oxygen ion conductivity, and an electrochemical device using the same.

The oxygen ion conductor of the present invention comprises an ion conducting part mainly composed of zirconium oxide containing at least one of calcium oxide, gadolinium oxide and rare earth oxide as a stabilizer, and a lanthanum chromite perovskite oxide. And a content of the zirconium oxide is higher than a content of the lanthanum chromite perovskite oxide.

  The electrochemical device of the present invention is characterized in that the oxygen ion conductor is disposed between a first electrode and a second electrode facing each other.

  According to the oxygen ion conductor of the present invention, an ion conducting portion mainly composed of zirconium oxide containing at least one of calcium oxide, gadolinium oxide and rare earth oxide as a stabilizer, and a lanthanum chromite-based perovskite oxidation An electron conducting part mainly composed of a substance, and the zirconium oxide content is higher than the content of the lanthanum chromite-based perovskite oxide, so that the density can be sufficiently increased, and more than the electrons. Oxygen ion conductivity can be increased because the content of zirconium oxide, which is a carrier of oxygen ions that is large in mass and easily controlled in movement, is relatively large.

  Further, according to the electrochemical device of the present invention, the oxygen ion conductor of the present invention is disposed between the first electrode and the second electrode facing each other, so that the purity is efficiently high. Oxygen can be obtained.

It is a perspective view which shows an example of the basic composition of the electrochemical apparatus of this embodiment. The other example of the basic composition of the electrochemical apparatus of this embodiment is shown, (a) is sectional drawing in a cross section perpendicular | vertical to a longitudinal direction, (b) is a perspective view which extracts and shows a part. It is a fragmentary sectional view in the cross section perpendicular | vertical to the longitudinal direction of the electrochemical apparatus of the example shown in FIG.

  The oxygen ion conductor of this embodiment is a zirconium oxide containing at least one of calcium oxide, gadolinium oxide, and a rare earth oxide as a stabilizer (hereinafter, stable at least one of calcium oxide, gallium oxide, and a rare earth oxide). Zirconium oxide as an agent is referred to as stabilized zirconia if there is no hindrance (note that stabilized zirconia also includes partially stabilized zirconia), and a lanthanum chromite perovskite type. An lanthanum chromite-based perovskite-type oxide comprising an electron-conducting portion whose main component is an lanthanum chromite-based perovskite-type oxide (hereinafter referred to as lanthanum chromite if there is no problem). It is important that the content is higher than the oxide content A. Here, the lanthanum chromite-based perovskite oxide is made of, for example, at least one of lanthanum magnesium chromite and lanthanum calcium chromite.

  If the oxygen ion conductor contains stabilized zirconia and lanthanum chromite, the density can be sufficiently increased, so that both the oxygen ion conductivity and the electron conductivity can be increased.

In addition, when a part of the chromium ions (Cr ³⁺ ) constituting the lanthanum chromite is replaced with at least one of magnesium ions (Mg ²⁺ ) and calcium ions (Ca ²⁺ ), many holes (holes) are generated. Electrons can easily move these holes, which is a factor for obtaining high electron conductivity.

In addition, since the zirconium oxide content is higher than the lanthanum chromite content, the mass is larger than that of electrons, and the content of zirconium oxide, which is a carrier for oxygen ions, which is easily controlled for movement, is relatively high. , Oxygen ion conductivity can be increased. In other words, in the oxygen ion conductor of the present embodiment, the amount of the ion conducting portion is larger than the amount of the electron conducting portion.

  In addition, the main component in the ion conduction part and the electron conduction part means a component in which the content of each component of interest is, for example, 80% by mass or more, and includes inevitable impurities such as aluminum and silicon other than the main component. There is nothing wrong with it.

Lanthanum chromite, for example, has a composition formula of La (Cr _1-x M _x ) _1-y O ₃ (M is at least one of magnesium and calcium. X is greater than 0 and 0.4 or less, y is 0 or more and 0.1 or less.), or LaCr _{1− (x + y)} M _x N _y O ₃ (M is at least one of magnesium and calcium, and N is nickel, iron, cobalt, zinc, And at least one of aluminum, copper, manganese, vanadium, and titanium, and x is greater than 0 and less than or equal to 0.2, and y is greater than 0 and less than or equal to 0.1.

  Here, the stabilized zirconia and lanthanum chromite contained in the oxygen ion conductor can be identified by using an X-ray diffraction method, and the contents of each of the stabilized zirconia and lanthanum chromite are determined by X-ray fluorescence analysis. Alternatively, it can be obtained by ICP (Inductively Coupled Plasma) emission spectroscopy. For example, the content of stabilized zirconia is determined by determining the respective contents of zirconium and the metal element constituting the stabilizer by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectroscopy. By converting to elemental oxides, the content of each oxide is calculated, and the total is the content of stabilized zirconia.

  On the other hand, the content of lanthanum chromite is obtained by calculating the content of lanthanum by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectrometry and converting it to lanthanum chromite identified using X-ray diffraction. Can be sought.

In the oxygen ion conductor of the present embodiment, the content of stabilized zirconia is preferably 56% by mass or more and 70% by mass or less with respect to 100% by mass in total of each content of stabilized zirconia and lanthanum chromite. is there. Since the content of stabilized zirconia is 56% by mass or more, the content of stabilized zirconia, which is a carrier for oxygen ions, is relatively higher, so that the oxygen ion conductivity can be further increased and stable. Since the content of lanthanum zirconia is 70% by mass or less, the content of lanthanum chromite is relatively increased and the electron conductivity can be increased, so that high oxygen ion conductivity and high electron conductivity are achieved. The oxygen ion conductor can also be provided.

In the oxygen ion conductor of the present embodiment, it is preferable that at least one of titanium, vanadium, manganese, iron, and cobalt is in solid solution in lanthanum chromite. With such a configuration, the production of lanthanum zirconate that reduces oxygen ion conductivity and electronic conductivity is suppressed, so that both of these characteristics can be maintained high.

The reason why the production of lanthanum zirconate is suppressed is not known in detail, but titanium, vanadium, manganese, iron, and cobalt are dissolved in the B site of lanthanum chromite to suppress the diffusion of lanthanum. It is considered possible.

In particular, the element dissolved in lanthanum chromite preferably has a content of 3 parts by mass or more and 15 parts by mass or less with respect to a total of 100 parts by mass of each content of stabilized zirconia and lanthanum chromite. When it is within the range, oxygen ion conductivity and electronic conductivity can be maintained high.

In the present embodiment, lanthanum chromite, composition formula, for _{example, La (Cr 1- (x +} y) M x N y) z O 3 (M is at least any one of magnesium and calcium, N is the calcium , Strontium, titanium, vanadium, manganese, iron and cobalt, and x and y are both greater than 0 and less than or equal to 0.3, and z is greater than or equal to 0.9 and less than or equal to 1 Yes.)

Here, lanthanum chromite in which at least one of titanium, vanadium, manganese, iron, and cobalt is dissolved is used in a stoichiometry using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. The composition and content can be determined.

  In addition, it is preferable that the oxygen ion conductor of the present embodiment includes magnesium oxide as one of the components constituting the electron conducting portion. When the oxygen ion conductor includes magnesium oxide, since the magnesium oxide has a large linear expansion coefficient, for example, the oxygen ion conductor is bonded to a metal member, or the first electrodes facing each other constituting the electrochemical device; When placed between the second electrode and the second electrode, the linear expansion coefficient of the metal member, the first electrode, and the second electrode can be brought close to each other, and reliability is easily obtained even when exposed to high temperatures. It becomes hard to be damaged.

In particular, the content of magnesium oxide is 4% by mass with respect to 100% by mass of lanthanum chromite.
The content is preferably 6% by mass or less, and within this range, the linear expansion coefficients of the metal member, the first electrode, and the second electrode can be made closer, and the reliability is improved.

  Magnesium oxide contained in the oxygen ion conductor can be identified using X-ray diffraction, and the content of magnesium oxide can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectroscopy. What is necessary is just to obtain | require an amount and to convert into magnesium oxide. However, when lanthanum chromite contains magnesium in its composition formula, first, the stoichiometric composition of lanthanum chromite is specified using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. And what is necessary is just to obtain | require content which remove | excluded the content of magnesium which comprises the lanthanum chromite in which the stoichiometric composition was specified from content of magnesium, and should just convert into magnesium oxide.

  In addition, it is preferable that the oxygen ion conductor of the present embodiment includes nickel oxide as one of the components constituting the electron conducting portion. When the oxygen ion conductor contains nickel oxide, the reductive expansion of the oxygen ion conductor (lattice expansion caused by the release of oxygen ions) is suppressed as the nickel oxide contracts due to the reduction, thereby increasing durability. be able to.

  Nickel oxide contained in the oxygen ion conductor can be identified by using an X-ray diffraction method, and the content thereof can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectroscopy. it can. However, when lanthanum chromite contains nickel in its composition formula, first, the stoichiometric composition of lanthanum chromite is specified using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. And what is necessary is just to obtain | require content which remove | excluded the content of nickel which comprises the lanthanum chromite in which stoichiometric composition was specified from content of nickel, and should just convert into nickel oxide.

In particular, the content of nickel oxide with respect to 100% by mass of lanthanum chromite is preferably 10% by mass or less, and when it is within this range, the crystal structure of lanthanum chromite is difficult to change and is stabilized.

Moreover, it is preferable that the oxygen ion conductor of this embodiment has an ion conduction part and an electron conduction part arranged adjacent to each other. When the ion conduction part and the electron conduction part are arranged adjacent to each other, the ion conduction part and the electron conduction part are compared with the case where components constituting the ion conduction part and the electron conduction part are mixed. Since the reactions of the components constituting each of the above are easily suppressed, oxygen ion conductivity and electron conductivity can be maintained high.

  In the oxygen ion conductor having the above-described configuration, since the lanthanum chromite-based perovskite oxide is difficult to sinter, it contains at least one of calcium oxide, gadolinium oxide, and rare earth oxide as a stabilizer. The density can be increased as the amount of zirconium oxide increases.

  From the above, the oxygen ion conductor of the present embodiment can have a sufficiently high density, and both the oxygen ion conductivity and the electron conductivity can be increased. By arranging the oxygen ion conductor described above between the (negative electrode) and the second electrode (positive electrode), the lanthanum chromite is moved from the first electrode (negative electrode) side to the second electrode (positive electrode) side. Electrons are moved to ionize oxygen dissociated from the gas, and stabilized zirconia moves the ionized oxygen ions to the second electrode (positive electrode) side and recombines them, so that high purity oxygen is obtained. The electrochemical device can be obtained.

  FIG. 1 is a perspective view showing an example of the basic configuration of the electrochemical device of the present embodiment.

  In the example of the electrochemical device 10 shown in FIG. 1, the oxygen ion conductor 1 is disposed between a first electrode 2 and a second electrode 3 facing each other. It is formed on the outer peripheral surface of the cylindrical support 4. Moreover, the gas flow path 6 is provided in the inside of the support body 4, and accompanying gas flows through this inside. In addition, it can also be set as the structure which has arrange | positioned the oxygen ion conductor 1 and the 2nd electrode 3 in the outer periphery in order with the 1st electrode 2 as a support body. Furthermore, the electrochemical device 10 is not limited to the cylindrical type, and the shape thereof can be changed as appropriate, for example, a flat plate type formed by laminating flat plates, an elliptical columnar type, and the like. It can also be set as the structure which does not provide.

The support body 4 has an outer diameter, a thickness, and a length of, for example, 8 to 9 mm, 1 to 2 mm, and 800 to 1200.
mm. The support 4 is composed of nickel oxide and yttrium oxide, and the contents of nickel oxide and yttrium oxide are 63 mass% or more and 73 mass% or less, and 27 mass% or more and 37 mass% or less, respectively.

  In other words, the first electrode 2 and the second electrode 3 are the fuel electrode 2 and the air electrode 3, respectively. The first electrode 2 may be an air electrode, and the second electrode 3 may be a fuel electrode.

In the case where the first electrode 2 is a fuel electrode, for example, the thickness is 10 μm or more and 50 μm or less, and the nickel electrode and the stabilized zirconia are included. It can be made from mass% to 70 mass%, from 30 mass% to 40 mass%. In addition, it can also comprise nickel oxide and a ceria-based oxide (for example, CeO ₂ in which Gd is dissolved).

In addition, when the thickness of the 1st electrode 2 is thin, what provided the support layer 5 which consists of the same composition as the support body 4 and provided the said 1st electrode in the support layer 5 is used for the support body 4 It may be pasted. In this case, for example, the support layer 5 has a thickness of 10 μm or more and 100 μm or less, and is composed of nickel oxide and yttrium oxide. Each content of nickel oxide and yttrium oxide is 63 mass% or more and 73 mass% or less, respectively. 27 mass% or more and 37 mass% or less. In addition, in FIG. 1, the example which provided the support layer 5 is shown.

  The second electrode 3 has a thickness of 10 μm or more and 50 μm or less, and can be composed of lanthanum strontium cobalt iron, lanthanum strontium manganite, or the like.

  2A and 2B show another example of the basic configuration of the electrochemical device of the present embodiment, in which FIG. 2A is a cross-sectional view in a cross section perpendicular to the longitudinal direction, and FIG. .

  The electrochemical device 20 of the example shown in FIG. 2 has a fuel electrode layer 22 as a first electrode so as to cover the entire circumference of a columnar support 24 composed of a pair of opposed flat portions n and arc-shaped portions m at both ends. A conductive layer 21 that is an oxygen ion conductor is provided so as to cover the fuel electrode layer 22, and an air electrode layer 23 that is a second electrode is provided so as to cover the conductive layer 21. . In addition, a plurality of gas flow paths 26 are provided inside the support 24, and accompanying gas flows through the inside. With such a configuration, a columnar electrochemical device 20 is formed.

  2 shows an electrochemical device 20 having a structure in which a fuel electrode layer 22 as a first electrode is provided on a hollow support 24 having a flat cross section. For example, the support 24 is a first support. The first electrode may be an air electrode layer, the second electrode may be a fuel electrode layer, and the whole is a cylindrical or flat electrochemical cell. You can also.

  Below, each member which comprises the electrochemical apparatus 20 shown in FIG. 2 is demonstrated. The conductive layer 21 will be described with reference to FIG.

  The support 22 is gas permeable so as to allow the associated gas flowing through the gas flow path 26 to permeate to the fuel electrode layer 23, which is the first electrode, so that, for example, an iron group metal component, a specific rare earth oxide, It is preferably formed by.

  Examples of the iron group metal component include an iron group metal simple substance, an iron group metal oxide, an iron group metal alloy, or an alloy oxide. More specifically, for example, the iron group metal includes Fe (iron), Ni (nickel) and Co (cobalt), and since it is particularly inexpensive, it contains Ni and / or NiO as the iron group component. Is preferred.

The specific rare earth oxide is used to bring the linear expansion coefficient of the support 24 close to the linear expansion coefficient of the conductive layer 21 described later. Y (yttrium), Lu (lutetium), Yb, Tm Rare earth oxide containing at least one element selected from the group consisting of (thulium), Er (erbium), Ho (holmium), Dy (dysprosium), Gd (gadolinium), Sm (samarium), Pr (praseodymium) However, it can be used in combination with at least one of Ni and NiO. Specific examples of such rare earth oxides include Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , Tm ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ , Dy ₂ O ₃ , Gd ₂ O. ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified, there is almost no solid solution reaction with at least one of Ni and NiO, and the linear expansion coefficient is almost the same as the linear expansion coefficient of the conductive layer 21. However, Y ₂ O ₃ and Yb ₂ O ₃ are preferable from the viewpoints of being moderate and inexpensive.

In addition, the support 24 maintains good conductivity and approximates the linear expansion coefficient to the conductive layer 21, so that the volume ratio after firing-reduction is Ni: rare earth oxide (for example, Ni: Y _2). O ₃ ) is preferably in the range of 35:65 to 65:35 (Ni / (Ni + Y) is 65 to 86 mol% in molar ratio). The support 24 may contain other metal components and oxide components as long as required characteristics are not impaired. Further, since the support 24 is required to have gas permeability, the porosity is preferably in the range of 30% by volume or more, particularly 35% by volume or more and 50% by volume or less. The porosity can be determined using the Archimedes method. When the porosity is within this range, the mechanical properties and gas permeability required for the support 24 constituting the electrochemical device 20 can be combined.

The size of the support 24 can be appropriately set according to the application. For example, the length of the main surface n (the length along the arrangement direction of the gas flow paths 26 of the support 24) is set. 15-35 mm, the length of the side m (arc length) is 2-8 mm, the thickness of the support 24 (thickness between the main surfaces n) is 1.5-5 mm,
The length in the direction in which the accompanying gas flows can be set to 800 to 1200 mm.

In the electrochemical device 20 shown in FIG. 2, the fuel electrode layer 22 as the first electrode may be formed from at least one of Ni and NiO as iron group metals and ZrO _{2 in} which a rare earth element is dissolved. it can. As the rare earth element, the rare earth elements exemplified in the support 24 (Y or the like) can be used.

In the fuel electrode layer 22, and at least one of Ni and NiO, ZrO ₂ content of the rare earth element is solid-solved is fired - volume ratio after reduction, Ni: ZrO ₂ (e.g. a rare earth element in solid solution, NiO: YSZ) is preferably in the range of 35:65 to 65:35. Further, the porosity of the fuel electrode layer 22 is preferably 15% by volume or more, particularly preferably in the range of 20% by volume or more and 40% by volume or less, and the thickness thereof is preferably 1 μm or more and 30 μm or less. For example, if the thickness of the fuel electrode layer 22 is too thin, the performance may be degraded, and if it is too thick, peeling or cracking may occur between the conductive layer 21 and the fuel electrode layer 22 due to a difference in thermal expansion coefficient, etc. There is.

In addition, in the electrochemical device 20 shown in FIG. 2, the air electrode layer 23 as the second electrode needs to have gas permeability. Therefore, the ceramic (perovskite oxide) forming the air electrode layer 23 is The porosity is preferably in the range of 20% by volume or more, particularly 30% by volume or more and 50% by volume or less. Furthermore, the thickness of the air electrode layer 23 is preferably 30 μm or more and 100 μm or less.

The ceramic constituting the air electrode layer 23 is preferably formed of a ceramic made of a sintered body mainly composed of a so-called ABO ₃ type perovskite type complex oxide, and is preferably a transition metal perovskite type oxide, particularly an A site. Sr (strontium) and La (lanthanum) coexist with LaSrCoFeO ₃ oxide (eg LaSrCoFeO ₃ ), LaMnO ₃ oxide (eg LaSrMnO ₃ ), LaFeO ₃ oxide (eg LaSrFeO ₃ ), LaCoO ₃ oxide At least one of the materials (for example, LaSrCoO ₃ ) is preferable, and LaSrCoFe is highly conductive at an operating temperature of about 600 to 1000 ° C.
O ₃ -based oxides are particularly preferable. In the perovskite oxide, Fe (iron) or Mn (manganese) may exist at the B site together with Co (cobalt).

  FIG. 3 is a partial cross-sectional view of a cross section perpendicular to the longitudinal direction of the example electrochemical device shown in FIG.

  As shown in FIG. 3, in the electrochemical device of this embodiment, the conductive layer 21 that is the oxygen ion conductor 1 has an ion conductive portion 21a that conducts oxygen ions and an electron conductive portion 21b that conducts electrons adjacent to each other. Are arranged. In the present embodiment, in plan view, the area of the ion conducting portion 21a mainly composed of zirconium oxide is made larger than the area of the electron conducting portion 21b mainly composed of a lanthanum chromite perovskite oxide. Thus, the content of zirconium oxide can be made larger than the content of the lanthanum chromite perovskite oxide. Note that the electrochemical device 10 shown in FIG. 1 can have the same configuration.

Since the oxygen ion conductivity of the oxygen ion conductor 1 (conductive layer 21) is increased from about 600 ° C., the associated gas is supplied to the first electrode (fuel electrode layer 22) in the temperature range of 600 ° C. or higher. Electrode (Air electrode layer 23
) Are each supplied with oxygen-containing gas. When the accompanying gas supplied to the first electrode (fuel electrode layer 22) is methane (CH ₄ ) gas, the methane (CH ₄ ) gas is transferred from the second electrode (air electrode layer 23) to the oxygen ion conductor. The oxygen ions moved through 1 (conductive layer 21) react with each other as shown in the following formula (1) to generate hydrogen, carbon monoxide and electrons. The generated electrons move from the first electrode (fuel electrode layer 22) to the second electrode (air electrode layer 23) through the oxygen ion conductor 1 (conductive layer 21), as shown in the following formula (2). To ionize oxygen molecules. By repeating the reactions shown in the following formulas (1) and (2), hydrogen and carbon monoxide are generated, and the generated gas is synthesized using, for example, the Fischer-Tropsch method (FT method). This makes it possible to create synthetic oils and synthetic fuels that can replace petroleum.

First electrode (fuel electrode layer 22): CH ₄ + O ²⁻ → 2H ₂ + CO + 2e ⁻ (1)
Second electrode (air electrode layer 23): 1 / 2O ₂ + 2e ⁻ → O ²⁻ (2)
Next, the manufacturing method of the oxygen ion conductor and the electrochemical device of the example shown in FIG. 1 of the present embodiment will be described.

  First, a paste of mixed powder containing nickel oxide powder as a main component and stabilized zirconia powder as a subcomponent on the outer peripheral surface of a cylindrical degreased body containing nickel oxide as a main component and yttrium oxide as a subcomponent. Apply using screen printing. In addition, when providing the support layer 5, the green sheet which consists of the same component as the component which comprises a degreasing | defatting body is wound around the outer peripheral surface of a cylindrical degreasing body, and the above-mentioned green sheet is formed by screen printing or the like. What is necessary is just to apply | coat a paste.

  Next, the cylindrical degreased body to which the paste is applied is heat-treated at, for example, a temperature and a holding time of 1150 ° C. or more and 1250 ° C. for 1 to 3 hours, respectively. A film is obtained by immersing the degreased body in a slurry containing each powder of stabilized zirconia and lanthanum chromite. For example, the temperature and the holding time are 1440 ° C. or higher and 1500 ° C. or lower and 1 hour or longer and 3 hours or shorter, respectively. Calcination in an air atmosphere. And by this baking, the cylindrical degreased body, the green sheet, the applied mixed powder paste and the film become the support 4, the first electrode 2, and the oxygen ion conductor 1, respectively.

  Here, each powder is mixed so that the respective contents of the stabilized zirconia and lanthanum chromite are, for example, 56 mass% to 70 mass% and 30 mass% to 44 mass%, respectively, to prepare a slurry. That's fine.

In addition, magnesium oxide powder can be appropriately added to the slurry to obtain oxygen ion conductor 1 containing magnesium oxide in an amount of 4% by mass to 6% by mass with respect to 100% by mass of lanthanum chromite.

Further, by appropriately adding nickel oxide powder to the slurry, the oxygen ion conductor 1 containing nickel oxide at 10% by mass or less with respect to 100% by mass of lanthanum chromite can be obtained.

And after forming the support body 4, the 1st electrode 2, and the oxygen ion conductor 1, the oxygen ion conductor 1 of the oxygen ion conductor 1 is immersed in the slurry containing the powder of lanthanum strontium cobalt iron. A film is obtained on the outer peripheral surface, and this film becomes, for example, a second electrode (air electrode) 3 by firing at a temperature and a holding time of 1100 ° C. or higher and 1200 ° C. or lower and 1 hour or longer and 3 hours or shorter, respectively. The electrochemical device of the present embodiment of the example shown in FIG. 1 can be obtained. In addition, the electrochemical device 10 then causes hydrogen gas to flow therein, and performs the reduction treatment of the support 4 and the first electrode (fuel electrode) 2. At that time, for example, it is preferable to perform a reduction treatment at 750 ° C. to 1000 ° C. for 5 hours to 20 hours.

  Next, a method for manufacturing the oxygen ion conductor (conductive layer) and the electrochemical device shown in FIG. 2 of the present embodiment will be described.

First, a clay is prepared by mixing a powder mainly composed of at least one of nickel and nickel oxide, a powder mainly containing a rare earth oxide such as yttrium oxide, an organic binder, and a solvent. A support molded body is prepared by an extrusion method using soil and dried. In addition, you may use the calcined body which calcined the support body molded object in 900 degreeC or more and 1000 degrees C or less for 2 hours or more and 6 hours or less as a support body molded object.

  Next, a slurry for the fuel electrode layer, which is the first electrode, is prepared by mixing an organic binder and a solvent with a mixed powder containing nickel oxide powder as a main component and stabilized zirconia powder as a subcomponent. A sheet-like fuel electrode layer molded body is formed by molding using a method such as a blade.

  Subsequently, the material for the electron conducting part (lanthanum chromite powder and, if necessary, powder comprising at least one of titanium oxide, vanadium oxide, manganese oxide, iron oxide and cobalt oxide, and further if necessary (Magnesium oxide powder, nickel oxide powder), an organic binder and a solvent are mixed to prepare a slurry, which is applied on the fuel electrode layer molded body with a screen printing method at intervals, and an electron conducting part molded body is formed. Make it.

Subsequently, the sheet of the fuel electrode layer molded body provided with the electron conductive portion molded body is wound so that the fuel electrode layer molded body is on the support body molded body side, and the temperature is 900 ° C. or higher and 1000 ° C. or lower for 2 hours. Calcination is performed for 6 hours or less.

  Next, after masking the molded body of the electron conducting part, toluene, an organic binder, a dispersant and the like are added to the stabilized zirconia powder containing at least one of calcium oxide, gallium oxide and rare earth oxide as a stabilizer. The slurry is prepared and immersed in the slurry to form an ion conductive portion molded body between the electron conductive portion molded bodies, thereby obtaining a laminate molded body. At this time, molding is performed so that the area of the ion conductive portion molded body is larger than the area of the electron conductive portion molded body. In addition, it is good also as the preparation order of an ion conduction part molded object and an electron conduction part molded object being reverse. Moreover, you may shape | mold so that an ion conduction part molded object and an electronic conduction part molded object may overlap partially.

  Next, the laminate compact is debindered and simultaneously sintered (simultaneously fired) in an oxygen-containing atmosphere at 1400 ° C. to 1600 ° C. for 2 hours to 6 hours.

Next, a slurry containing an air electrode layer material (for example, LaSrCoFeO ₃ -based oxide or (La, Sr) MnO ₃ -based oxide powder), a solvent, and a pore-forming agent is subjected to dipping or the like to cause ion conduction portion 21a and electrons. The electrochemical device 20 having the structure shown in FIG. 2 can be obtained by coating on the conductive portion 21b and baking at 1000 to 1300 ° C. for 2 to 6 hours. In addition, the electrochemical device 20 then causes hydrogen gas to flow therein and performs a reduction treatment of the support 24 and the fuel electrode layer 22. At that time, for example, it is preferable to perform a reduction treatment for 750 ° C. to 1000 ° C. for 5 hours to 20 hours.

  Since the electrochemical device manufactured as described above includes the conductive layer 21 that is an oxygen ion conductor that can maintain both oxygen ion conductivity and electron conductivity high, the associated gas is efficiently decomposed. be able to.

In addition, the electrochemical device 20 includes a conductive layer 21 in which an ion conductive portion 21a and an electron conductive portion 21b are provided adjacent to each other, and a first electrode provided so as to cover one surface of the conductive layer 21. (Air electrode layer) 22 and a second second electrode (fuel electrode layer) 23 provided so as to cover the other surface of the conductive layer 21, and on the porous support 24, the first electrode Since the electrode (air electrode layer) 22, the conductive layer 21, and the second electrode (fuel electrode layer) 23 are laminated in this order, the associated gas can be efficiently decomposed.

The accompanying gas can be efficiently decomposed by providing a plurality of the electrochemical device cells 10 and 20 described above. Furthermore, one end of the electrochemical devices 10 and 20 is fixed to the accompanying gas tank for supplying the accompanying gas to the electrochemical devices 10 and 20, and the other end of the electrochemical devices 10 and 20 is generated in the hydrogen gas tank generated by decomposing the accompanying gas. By fixing the gas, the accompanying gas can be efficiently decomposed and the hydrogen gas generated by the decomposition can be efficiently recovered.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, in the above-described example, the example in which the conductive support 24 is used as the support 24 has been described. However, in the case where a conductive layer is provided on the surface of the support 24, the support 24 is insulated. It can also be sex.

  In the above example, the configuration in which one layer of the fuel electrode layer 22 is provided on the support 24 has been described. However, the conduction of electrons and ions between the fuel electrode layer 22 and the air electrode layer 23 is more efficient. When performing well, a layer made of a more conductive material may be provided between the fuel electrode layer 22 and the support 24.

  Further, when the electrochemical device 20 is a cylindrical type or a flat plate type, the first electrode and the ion conducting unit and the electron conducting unit are adjacently provided so as to cover the first electrode by a known method as appropriate. The conductive layer may be provided, and the second electrode may be provided so as to cover the conductive layer.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

  First, powders of the respective components were prepared so that the components constituting the oxygen ion conductor had the types and contents shown in Table 1 as sintered bodies.

  Then, toluene is added as an organic solvent to the prepared powder, and after pulverizing and mixing using a mill, a predetermined amount of paraffin wax is added as a binder, and molding is performed at a pressure of 98 MPa using a dry pressure molding method. As a result, a disk shaped body was obtained.

  And after arrange | positioning a molded object to an electric furnace, the temperature was kept at 1460 degreeC in air | atmosphere for 2 hours, and the disk-shaped sintered compact whose diameter and thickness were 15 mm and 0.2 mm was obtained, respectively.

Then, a first electrode having a content of nickel oxide and stabilized zirconia of 65% by mass and 35% by mass, respectively, is provided on one main surface of the sintered body, and lanthanum strontium manganate on the other main surface of the sintered body. Sample No. 2 for forming a second electrode made of knight and evaluating oxygen ion conductivity was prepared. 1-16 were obtained.

  In addition, the composition formula showing the component of the stabilized zirconia shown in Table 1 is that the first number is the content of the stabilizer and the next alphabet is the metal component of the stabilizer. For example, if it is 8YSZ, % Zirconium oxide containing 1% yttrium oxide as a stabilizer.

  Then, using an oxygen permeation tester, each sample is fixed at a predetermined position in a cylinder for supplying gas, argon gas containing 30% by volume of methane on the first electrode side, and second electrode Air was supplied to each side, and the oxygen transmission rate was measured.

  Table 1 shows the components constituting each sample, their contents, and the oxygen permeation amount of each sample.

  As can be seen from the results shown in Table 1, Sample No. 1 to 3 and 5 to 16 include an ion conducting portion mainly composed of zirconium oxide containing at least one of calcium oxide, gadolinium oxide and rare earth oxide as a stabilizer, and a lanthanum chromite perovskite oxide. It has an electron conduction part as the main component, and the content of zirconium oxide is higher than the content of lanthanum chromite perovskite oxide, so the content of zirconium oxide is relatively high, so oxygen ion conduction Sexuality can be increased.

  First, in the oxygen ion conductor, zirconium oxide containing 8 mol% of yttrium oxide as a stabilizer as a component constituting the ion conducting portion, lanthanum magnesium chromite and manganese oxide as components constituting the electron conducting portion, The powder of each component was prepared so that the content of the components was 56% by mass and 44% by mass as the sintered body, and the content shown in Table 2. However, the content of manganese oxide is a content with respect to a total of 100 parts by mass of each content of zirconium oxide and lanthanum magnesium chromite.

  Sample No. 1 which is a prismatic sintered body having a length, a width and a thickness of 20 mm, 5 mm and 5 mm, respectively, by the same method as shown in Example 1. 17-22 were obtained.

  And the presence or absence of lanthanum zirconate was confirmed by X-ray diffraction. Table 2 shows the presence of lanthanum zirconate in samples that were confirmed and the absence of lanthanum zirconate in samples.

  The mixed conductivity, which is the sum of the ionic conductivity and the electron conductivity, was measured at a temperature of 1000 ° C. by the four-terminal method, and the measured values are shown in Table 2.

  As can be seen from the results shown in Table 2, the sample No. In 18-22, since manganese is dissolved in lanthanum magnesium chromite, which is a perovskite oxide, the production of lanthanum zirconate, which reduces oxygen ion conductivity and electron conductivity, is suppressed. It can be seen that the characteristics are all high.

First, in the oxygen ion conductor, zirconium oxide containing 8 mol% of yttrium oxide as a stabilizer as a component constituting the ion conducting portion, lanthanum magnesium chromite and magnesium oxide as components constituting the electron conducting portion, The powders of the respective components were prepared so that the content of was 56% by mass and 44% by mass as a sintered body, and the content shown in Table 3 (magnesium oxide was content relative to 100% by mass of lanthanum magnesium chromite). However, the content of magnesium oxide is the content with respect to lanthanum magnesium chromite.

  Sample No. 1 which is a prismatic sintered body having a length, a width and a thickness of 20 mm, 5 mm and 5 mm, respectively, by the same method as shown in Example 1. 23-27 were obtained.

  Moreover, the linear expansion coefficient from room temperature to 1000 ° C. of each sample was determined according to JIS R 1618-2002, and the measured values are shown in Table 3.

As can be seen from the results shown in Table 3, Sample No. Since 24 to 27 contain magnesium oxide having a large linear expansion coefficient as a component constituting the electron conducting portion, the first electrode 2 and the second electrode facing each other that constitute the electrochemical device 10 with the oxygen ion conductor are used. In the case of being arranged between the electrodes 3, the linear expansion coefficients of the first electrode 2 and the second electrode 3 are 10 × 10 ⁻⁶ / ° C. (measurement range: room temperature) rather than the sample No. 23 containing no magnesium oxide. It can be said that reliability is not easily lost even when exposed to high temperatures. The same applies to the case where the oxygen ion conductor is disposed between the first electrode 22 and the second electrode 23 that constitute the electrochemical device 20 facing each other.

Note that Sample No. containing a large amount of magnesium oxide was used. No. 27 is a document No. containing no magnesium oxide. Although the linear expansion coefficient of the first electrode 2 and the second electrode 3 can be closer to 10 × 10 ⁻⁶ / ° C. (measurement range: room temperature to 1000 ° C.) than 23, the effect is low.

  An electrochemical device provided with a support layer was produced by the following method.

  First, the green sheet which consists of the same component as the component which comprises a degreasing | defatting body was wound around the outer peripheral surface of the cylindrical degreasing | defatting body whose nickel oxide and yttrium oxide are 68 mass% and 32 mass%, respectively. Next, a paste of mixed powder in which the nickel oxide powder and the stabilized zirconia powder are 65% by mass and 35% by mass, respectively, is applied onto the green sheet by using a screen printing method, and the temperature and holding time are 1190 respectively. Heat treatment was performed at 2 ° C. for 2 hours. Then, the degreased body is added to a slurry containing zirconium oxide containing 8 mol% of yttrium oxide as a stabilizer as a component constituting the ion conductive portion and lanthanum magnesium chromite and nickel oxide powders as components constituting the electron conductive portion. By dipping, a film was formed, and the temperature and holding time were 1460 ° C. and 2 hours, respectively, and firing was performed in an air atmosphere. In addition, the powder was prepared so that nickel oxide might become content shown in Table 4 as a sintered compact. And by this firing, the cylindrical degreased body, the green sheet, the paste and the coating of the applied mixed powder are respectively transferred to the support 4, the support layer 5, the first electrode (fuel electrode) 2, and the oxygen ion conductor 1. did.

  Here, the contents of zirconium oxide, lanthanum magnesium chromite and nickel oxide containing yttrium oxide contained in the oxygen ion conductor 1 as stabilizers are 56 mass% and 44 mass%, respectively, as sintered bodies. The powder of each component was prepared so that it might be shown content (nickel oxide is content with respect to 100 mass% of lanthanum magnesium chromite).

  And after forming the support body 4, the support layer 5, the 1st electrode 2, and the oxygen ion conductor 1, oxygen ion conductor 1 is immersed in the slurry containing the powder of a lanthanum strontium cobalt iron, oxygen ion A film was formed on the outer peripheral surface of the conductor 1. Then, by baking at a temperature and a holding time of 1140 ° C. for 2 hours, respectively, a second electrode (air electrode) 3 is obtained, and the sample No. 1 which is the electrochemical device 10 of the present embodiment of the example shown in FIG. Ten samples 28 to 31 were prepared for each sample.

Then, methane (CH ₄ ) gas was supplied to the inside of the support 4, and air was supplied to the outer peripheral side of the second electrode 3. After holding at 850 ° C. for 100 hours, cooling, using an optical microscope, Cracks were observed on the end face of the oxygen ion conductor 1 on the side supplied with methane (CH ₄ ) gas at a magnification of 50 times. Table 4 shows the ratio of samples in which cracks were observed.

  As can be seen from the results shown in Table 4, sample No. Since 29 to 31 contain nickel oxide, reductive expansion of the oxygen ion conductor is suppressed as the nickel oxide contracts due to reduction, so cracks are less likely to occur and durability is increased. Can be said.

1,21: Oxygen ion conductor (conductive layer)
2, 22: First electrode (fuel electrode, fuel electrode layer)
3, 23: Second electrode (air electrode, air electrode layer)
10, 20: Electrochemical equipment

Claims (6)

  An ion conducting part mainly composed of zirconium oxide containing at least one of calcium oxide, gadolinium oxide and rare earth oxide as a stabilizer, and an electron conducting part mainly composed of a lanthanum chromite perovskite oxide. And an oxygen ion conductor characterized in that the zirconium oxide content is greater than the content of the lanthanum chromite perovskite oxide. 2. The oxygen ion conductor according to claim 1, wherein at least one of titanium, vanadium, manganese, iron and cobalt is dissolved in the perovskite oxide.   The oxygen ion conductor according to claim 1 or 2, characterized by containing magnesium oxide.   The oxygen ion conductor according to any one of claims 1 to 3, further comprising nickel oxide.   The oxygen ion conductor according to any one of claims 1 to 4, wherein the ion conducting portion and the electron conducting portion are disposed adjacent to each other.   6. An electrochemical device, wherein the oxygen ion conductor according to claim 1 is disposed between a first electrode and a second electrode facing each other.

Images