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US-20260128342-A1 - PROTON CONDUCTOR, FILM-ELECTRODE JOINED BODY, ELECTROCHEMICAL CELL, AND FUEL CELL STACK

US20260128342A1US 20260128342 A1US20260128342 A1US 20260128342A1US-20260128342-A1

Abstract

A proton conductor of the present disclosure contains a compound represented by a chemical formula Ba a Zr 1-x-y Yb x Cu y O 3-δ . In the chemical formula. 0.95≤a≤1.05, 0.1≤x≤0.4.0.01<<0.20, and 0<δ≤0.65 are satisfied. An electrolyte film of the present disclosure contains the proton conductor of the present disclosure.

Inventors

  • Yuichi MIKAMI
  • KOSUKE NUNOO
  • Tomohiro Kuroha
  • Yuji Okuyama

Assignees

  • PANASONIC HOLDINGS CORPORATION

Dates

Publication Date
20260507
Application Date
20251107
Priority Date
20230515

Claims (9)

  1. 1 . A proton conductor comprising a compound represented by a chemical formula Ba a Zr 1-x-y Yb x Cu y O 3-δ , wherein 0.95≤a≤1.05, 0.1≤x≤0.4, 0.01<y<0.20, and 0<8≤0.65 are satisfied.
  2. 2 . The proton conductor according to claim 1 , wherein in the chemical formula, 0.04≤y≤0.16 is satisfied.
  3. 3 . The proton conductor according to claim 2 , wherein in the chemical formula, 0.125≤y≤0.16 is satisfied.
  4. 4 . The proton conductor according to claim 3 , wherein in the chemical formula, 0.125≤y≤0.15 is satisfied.
  5. 5 . The proton conductor according to claim 4 , wherein in the chemical formula, y=0.15 is satisfied.
  6. 6 . An electrolyte film comprising the proton conductor according to claim 1 .
  7. 7 . A film-electrode joined body comprising: the electrolyte film according to claim 6 ; and an electrode provided on the electrolyte film.
  8. 8 . An electrochemical cell comprising: a first electrode; a second electrode; and the electrolyte film according to claim 6 provided between the first electrode and the second electrode.
  9. 9 . A fuel cell stack comprising a plurality of the electrochemical cells according to claim 8 .

Description

BACKGROUND 1. Technical Field The present disclosure relates to a proton conductor, a film-electrode joined body, an electrochemical cell, and a fuel cell stack. 2. Description of the Related Art A solid oxide fuel cell (hereinafter referred to as the “SOFC”) is a fuel cell in which a solid oxide is used for an electrolyte constituting an electrolyte film. As the solid oxide as the electrolyte, oxide ion conductors represented by stabilized zirconia are widely being used and have an advantage in that they have higher power generation efficiency than a polymer electrolyte fuel cell (PEFC). A proton-conducting ceramic fuel cell (hereinafter referred to as the “PCFC”), a kind of the SOFC, has a feature of containing a solid oxide having proton conductivity for the electrolyte constituting the electrolyte film. In general SOFCs, water vapor is generated at a fuel electrode through a power generation reaction. For this reason, in an operating environment with a high fuel usage rate, hydrogen as a fuel is diluted with the water vapor, and the electromotive force of the fuel cell reduces or the risk of deterioration of the cell due to fuel exhaustion increases. Given these circumstances, general SOFCs cannot sufficiently increase the fuel usage rate. Meanwhile, in the PCFC containing the proton conductor for the electrolyte, the generation of water vapor by the power generation reaction proceeds at an air electrode, thus inhibiting dilution of hydrogen at the fuel electrode. This can maintain the electromotive force of the fuel cell at a high level even when operated with a high fuel usage rate and can also reduce the risk of fuel exhaustion, thus providing an advantage in operation with a high fuel usage rate. The power generation efficiency of the fuel cell is represented by the product of the voltage of the cell and the fuel usage rate, and thus the PCFC, which can achieve both a high fuel usage rate and a high electromotive force, is expected to have a particularly high power generation efficiency among SOFCs. The ability of maintaining the high electromotive force also leads to the ability of operating the fuel cell with an increased current density, thus providing an advantage also in terms of higher output. To aim at higher power generation efficiency and higher output in the PCFC, it is important to reduce the internal resistance of the cell during power generation, and for this purpose, it is important to improve the proton conductivity of the proton conductor used as the electrolyte. As general proton conductors, materials in which the sites of Zr or Ce of each of BaZrO3, BaCeO3, and Ba(Ce,Zr)O3, which have the perovskite structure, are partially substituted by metallic elements having +3 valence, such as yttrium (Y) or ytterbium (Yb), are used. It is known that these materials have relatively high proton conductivity. The BaZrO3-based proton conductor in particular has relatively high chemical stability against CO2 contained in a fuel gas of the fuel cell or the air and attracts attention. In the case of the BaZrO3-based proton conductor, when Y is used as a substitution element, BaY2NiO5-δ (δ is the number of oxygen vacancies) as a by-product is likely to occur with NiO used for the fuel electrode at a high temperature. Note that 8 represents the number of oxygen vacancies. The generation of BaY2NiO5-δ leads to a reduction in the performance and reliability of the fuel cell. In contrast, the use of Yb as the substitution element provides an advantage in that by-products are hard to occur. Thus, the material containing Yb as the substitution element in the BaZrO3-based proton conductor is considered to be a promising material in practical use. If the proton conductivity can be further improved based on the Yb-substituted BaZrO3, that provides an advantage to achieve the fuel cell having high power generation efficiency or high output density. J. Park et al., “Low temperature sintering of BaZrO3-based proton conductors for intermediate temperature solid oxide fuel cells”, Solid State Ionics 181 163-167 (2010) studies further addition of CuO for the Yb-substituted BaZrO3. According to J. Park et al., “Low temperature sintering of BaZrO3-based proton conductors for intermediate temperature solid oxide fuel cells”, Solid State Ionics 181 163-167 (2010), by adding 1.0 mol % of CuO to the Yb-substituted BaZrO3, an effect of promoting the sintering of the Yb-substituted BaZrO3 is produced. SUMMARY According to J. Park et al., “Low temperature sintering of BaZrO3-based proton conductors for intermediate temperature solid oxide fuel cells”, Solid State Ionics 181 163-167 (2010), by adding 1.0 mol % of CuO, the sinterability of the Yb-substituted BaZrO3 improves, but the Yb-substituted BaZrO3 substituted by 1.0 mol % of CuO obtained thereby reduces in proton conductivity compared to one that does not contain Cu. One non-limiting and exemplary embodiment provides a proton conductor capable of being used for the PC