Search

EP-3719815-B1 - PROTON CONDUCTOR, PROTON-CONDUCTING CELL STRUCTURE, WATER VAPOR ELECTROLYSIS CELL, AND METHOD FOR PRODUCING HYDROGEN ELECTRODE-SOLID ELECTROLYTE LAYER COMPLEX

EP3719815B1EP 3719815 B1EP3719815 B1EP 3719815B1EP-3719815-B1

Inventors

  • HIGASHINO, Takahiro
  • ONISHI, TAKAYUKI
  • NODA, YOHEI
  • HIRAIWA, CHIHIRO
  • MIZUHARA, NAHO
  • OGAWA, MITSUYASU
  • TAWARAYAMA, HIROMASA
  • MAJIMA, MASATOSHI
  • UDA, TETSUYA
  • HAN, Donglin

Dates

Publication Date
20260506
Application Date
20181116

Claims (11)

  1. A proton-conducting cell structure comprising an oxygen electrode, a hydrogen electrode, and a proton conductor interposed between the oxygen electrode and the hydrogen electrode, the proton conductor containing a metal oxide that has a perovskite structure and that is represented by the following formula (1): A x B 1-y M y O 3-δ (1), where an element A is at least one element selected from the group consisting of Ba, Ca, and Sr, an element B is at least one element selected from the group consisting of Ce and Zr, an element M is at least one element selected from the group consisting of Y, Yb, Er, Ho, Tm, Gd, In, and Sc, δ indicates an oxygen deficiency amount, and 0.95≤x≤1 and 0<y≤0.5 are satisfied; wherein: the hydrogen electrode contains nickel, and a ratio R Ni of Ni contained in the proton conductor to a total amount of the element A, the element B, and the element M contained in the proton conductor is equal to or less than 1.2 at%; and wherein: the hydrogen electrode further contains an element X different from any of the element A, the element B, and the element M, wherein the element X includes at least Mg.
  2. The proton-conducting cell structure according to claim 1, wherein a transport number of ionic conduction of the proton conductor in a humidified oxygen atmosphere at 600°C is equal to or greater than 0.8.
  3. The proton-conducting cell structure according to claim 1 or 2, wherein the formula (1) satisfies 0.98≤x≤1.
  4. The proton-conducting cell structure according to any one of claims 1 to 3, wherein the element A includes Ba, the element B includes Zr, and the element M includes Y.
  5. The proton-conducting cell structure according to any one of claims 1 to 4, wherein the element X is capable of forming a compound containing Ni.
  6. The proton-conducting cell structure according to any one of claims 1 to 5, wherein the ratio R Ni of Ni is equal to or less than 1.0 at%.
  7. A water vapor electrolysis cell comprising the proton-conducting cell structure according to any one of claims 1 to 6.
  8. A method for producing a hydrogen electrode-solid electrolyte layer complex, the method comprising: a first step of obtaining a cell precursor in which a porous first solid electrolyte layer and a dense second solid electrolyte layer are integrated with each other; and a second step of providing a nickel component in pores of the first solid electrolyte layer, wherein each of the first solid electrolyte layer and the second solid electrolyte layer contains a metal oxide that has a perovskite structure and that is represented by the following formula (1): A x B 1-y M y O 3-δ (1), where an element A is at least one element selected from the group consisting of Ba, Ca, and Sr, an element B is at least one element selected from the group consisting of Ce and Zr, an element M is at least one element selected from the group consisting of Y, Yb, Er, Ho, Tm, Gd, In, and Sc, δ indicates an oxygen deficiency amount, and 0.95≤x≤1 and 0<y≤0.5 are satisfied; wherein: the first solid electrolyte layer further contains an element X different from any of the element A, the element B, and the element M, wherein the element X includes at least Mg; and a ratio R Ni of Ni contained in the second solid electrolyte layer to a total amount of the element A, the element B, and the element M contained in the second solid electrolyte layer is equal to or less than 1.2 at%.
  9. The method for producing a hydrogen electrode-solid electrolyte layer complex according to claim 8, wherein a transport number of ionic conduction of the second solid electrolyte layer in a humidified oxygen atmosphere at 600°C is equal to or greater than 0.8.
  10. The method for producing a hydrogen electrode-solid electrolyte layer complex according to claim 8 or 9, wherein the first step includes: a step of obtaining a paste laminate by laminating a first paste layer containing a raw material of the first solid electrolyte layer and a pore forming material and a second paste layer containing a raw material of the second solid electrolyte layer and not containing the pore forming material; and a step of firing the paste laminate at 400°C to 1000°C.
  11. The method for producing a hydrogen electrode-solid electrolyte layer complex according to any one of claims 8 to 10, wherein the second step includes firing at 200°C to 600°C after a nickel compound solution is contained in the pores.

Description

TECHNICAL FIELD The present disclosure relates to a proton conductor (not claimed), a proton-conducting cell structure, a water vapor electrolysis cell, and a method for producing a hydrogen electrode-solid electrolyte layer complex. This application claims priority on Japanese Patent Application No. 2017-229685 filed on November 29, 2017, and Japanese Patent Application No. 2018-030074 filed on February 22, 2018. BACKGROUND ART A proton conductive metal oxide having a perovskite structure has been known as a solid electrolyte that can be applied to PCFCs (Protonic Ceramic Fuel Cells, proton conductive oxide type fuel cells) using hydrogen ions (protons) as charge carriers (PATENT LITERATURE 1 and PATENT LITERATURE 2). Proton conductors, cell structures, methods for producing a proton conductor and cell structure are known from PATENT LITERATURE 3 and PATENT LITERATURE 4. CITATION LIST [PATENT LITERATURE] PATENT LITERATURE 1: Japanese Laid-Open Patent Publication No. 2001-307546PATENT LITERATURE 2: Japanese Laid-Open Patent Publication No. 2007-197315PATENT LITERATURE 3: WO 20171104806 A1PATENT LITERATURE 4: WO 2017/030023 A1 SUMMARY OF INVENTION A proton conductor of the present disclosure contains a metal oxide that has a perovskite structure and that is represented by the following formula (1):         AxB1-yMyO3-δ     (1), where an element A is at least one element selected from the group consisting of Ba, Ca, and Sr,an element B is at least one element selected from the group consisting of Ce and Zr,an element M is at least one element selected from the group consisting of Y, Yb, Er, Ho, Tm, Gd, In, and Sc,δ indicates an oxygen deficiency amount, and0.95≤x≤1 and 0<y≤0.5 are satisfied. A proton-conducting cell structure of the present disclosure includes an oxygen electrode, a hydrogen electrode, and the proton conductor of the present disclosure interposed between the oxygen electrode and the hydrogen electrode. A water vapor electrolysis cell of the present disclosure includes the proton-conducting cell structure of the present disclosure. A method for producing a hydrogen electrode-solid electrolyte layer complex of the present disclosure includes: a first step of obtaining a cell precursor in which a porous first solid electrolyte layer and a dense second solid electrolyte layer are integrated with each other; anda second step of providing a nickel component in pores of the first solid electrolyte layer, whereineach of the first solid electrolyte layer and the second solid electrolyte layer contains a metal oxide that has a perovskite structure and that is represented by the following formula (1):         AxB1-yMyO3-δ     (1), where an element A is at least one element selected from the group consisting of Ba, Ca, and Sr,an element B is at least one element selected from the group consisting of Ce and Zr,an element M is at least one element selected from the group consisting of Y, Yb, Er, Ho, Tm, Gd, In, and Sc,δ indicates an oxygen deficiency amount, and0.95≤x≤1 and 0<y≤0.5 are satisfied. A proton-conducting cell structure, a water vapor electrolysis cell, and a method for producing a hydrogen electrode-solid electrolyte layer complex of the invention are as defined in claims 1, 7 and 8, respectively. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view schematically showing a proton-conducting cell structure according to an embodiment of the present disclosure.FIG. 2 is a diagram showing a relationship between a Ba deficiency amount and a transport number of ionic conduction in a proton conductor according to an embodiment of the present disclosure.FIG. 3 is a diagram showing an Arrhenius plot for a proton conductor according to an embodiment of the present disclosure.FIG. 4 is a diagram showing a relationship between an ambient temperature and a transport number of ionic conduction in a proton conductor according to an embodiment of the present disclosure.FIG. 5 is a diagram showing a relationship between a ratio (RNi) of Ni contained in a proton conductor according to an embodiment of the present disclosure and total conductivity at 600°C in a hydrogen atmosphere.FIG. 6 is a diagram showing a relationship between RNi and a Y concentration in a solid electrolyte layer of a hydrogen electrode-solid electrolyte layer complex according to an embodiment of the present disclosure. DESCRIPTION OF EMBODIMENTS [TECHNICAL PROBLEM] For a cell structure in which yttria-stabilized zirconia (YSZ) is used for a solid electrolyte layer, a configuration in which a hydrogen electrode obtained by mixing NiO and a solid electrolyte is used as a support for a thinned solid electrolyte layer has been studied. Even with a proton conductive metal oxide, it is possible to make the solid electrolyte layer thinner by the above configuration. However, the cell structure is formed by co-sintering a hydrogen electrode and a solid electrolyte layer. During co-sintering, when Ni of the hydrogen electrode diffuses