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WO2025054305A1 - Piles électrochimiques céramiques protoniques ayant une électrode positive composite - Google Patents

Piles électrochimiques céramiques protoniques ayant une électrode positive composite Download PDF

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Publication number
WO2025054305A1
WO2025054305A1 PCT/US2024/045358 US2024045358W WO2025054305A1 WO 2025054305 A1 WO2025054305 A1 WO 2025054305A1 US 2024045358 W US2024045358 W US 2024045358W WO 2025054305 A1 WO2025054305 A1 WO 2025054305A1
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Prior art keywords
positive electrode
perovskite phase
electrochemical cell
solid composite
molar ratio
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English (en)
Inventor
Chuancheng Duan
Fan Liu
Liyang FANG
Nilesh Dale
Hussain JABBAR
Cenk Gumeci
Yoshihisa FURUYA
Takanori Oku
Masahiro Usuda
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Nissan Motor Co Ltd
Kansas State University
Nissan North America Inc
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Nissan Motor Co Ltd
Kansas State University
Nissan North America Inc
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Publication of WO2025054305A1 publication Critical patent/WO2025054305A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
    • C01G25/006—Compounds containing zirconium, with or without oxygen or hydrogen, and containing two or more other elements
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Complex oxides containing cobalt and at least one other metal element
    • C01G51/66—Complex oxides containing cobalt and at least one other metal element containing alkaline earth metals, e.g. SrCoO3
    • C01G51/68—Complex oxides containing cobalt and at least one other metal element containing alkaline earth metals, e.g. SrCoO3 containing rare earths, e.g. (La0.3Sr0.7)CoO3
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/052—Electrodes comprising one or more electrocatalytic coatings on a substrate
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
    • H01M4/9025—Oxides specially used in fuel cell operating at high temperature, e.g. SOFC
    • H01M4/9033—Complex oxides, optionally doped, of the type M1MeO3, M1 being an alkaline earth metal or a rare earth, Me being a metal, e.g. perovskites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • C25B11/077—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the compound being a non-noble metal oxide
    • C25B11/0773—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the compound being a non-noble metal oxide of the perovskite type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
    • H01M2004/8689—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present disclosure generally relates to positive electrodes that can be used in protonic ceramic electrochemical cells (“PCECs”). More particularly, the present disclosure generally relates to positive electrodes that comprise a solid composite material comprising a double perovskite phase and a single perovskite phase.
  • PCECs protonic ceramic electrochemical cells
  • the present disclosure generally relates to positive electrodes that comprise a solid composite material comprising a double perovskite phase and a single perovskite phase.
  • PCECs protonic ceramic electrochemical cells
  • Haile et al. demonstrated that depositing a dense interfacial layer between the electrolyte and positive electrode reduced the ohmic resistance and increased the PPD to 0.36 W cm -2 on H2-air at 450°C. To reduce the electrode polarization resistance, Ding et al.
  • PrBa0.5Sr0.5Co1.5Fe0.5O6- ⁇ (“PBSCF-1”) positive electrode using a complicated template method, which improved the mass transport kinetics, leading to a PPD of 0.41 W cm -2 on H2-O2 at 400°C.
  • PBSCF-1 PrBa0.5Sr0.5Co1.5Fe0.5O6- ⁇
  • a recent study by the same team reported that employing an acid-etched electrolyte and a positive electrode fabricated via this template method further increased the PPD to 0.65 W cm -2 on H2-O2 at 450°C.
  • most of these approaches are either complicated or unscalable. Therefore, more straightforward and scalable methods are desired to fabricate PCECs with low- resistance electrolytes and active positive electrodes to achieve good PCEC performance at ⁇ 450°C.
  • PCECs contribute additional ohmic resistance, which mainly includes high electrolyte-grain boundary resistance, and positive electrode-electrolyte contact resistance. Therefore, PCECs should be better fabricated to optimize their microstructure, aiming at minimizing the grain boundary resistance while enhancing the bonding between the electrode and electrolyte, particularly the weakly bonded positive electrode-electrolyte interface created in a separated high-temperature step. Furthermore, it has been widely recognized that the oxygen reduction reaction (“ORR”) and oxygen evolution reaction (“OER”), which occur at the positive electrode, tend to be more sluggish with decreasing operating temperatures.
  • ORR oxygen reduction reaction
  • OER oxygen evolution reaction
  • One or more embodiments generally relate to a positive electrode that can be used in protonic ceramic electrochemical cells (PCECs) that comprises a solid composite material comprising a double perovskite phase and a single perovskite phase.
  • the double perovskite phase comprises PrBaSrCoFeO (PBSCF) and the single perovskite phase comprises BaSrCoO (BSC).
  • PCECs protonic ceramic electrochemical cells
  • PBSCF PrBaSrCoFeO
  • BSC BaSrCoO
  • One or more embodiments generally relate to a positive electrode that comprises a solid composite material.
  • the solid composite material comprises a double perovskite phase having a formula PraBabSrcCodFeeO6- ⁇ 1 and a single perovskite phase having a formula BaxSryCozO3- ⁇ 2, wherein a is from 1 to 1.75; b is from 0.05 to 0.5; c is from 0.3 to 0.7; d is from 1.25 to 1.75; e is from 0.4 to 0.9; ⁇ 1 is greater than zero, but less than 1; x is from 0.4 to 0.75; y is from 0.25 to 0.5; z is from 0.75 to 1.25; and ⁇ 2 is greater than zero, but less than 0.5.
  • One or more embodiments generally relate to a protonic ceramic electrochemical cell (PCEC) comprising a positive electrode formed from a solid composite material according to any embodiment described herein.
  • the PCEC further comprises a negative electrode that comprises any material conventional for such electrodes, including, but not limited to, BCZYYb7111 and NiO.
  • the PCEC also comprises an electrolyte located between the oxygen and fuel electrodes.
  • the electrolyte can be any conventional electrolyte material, including, but not limited to BCZYYb4411.
  • the positive and negative electrodes have a thickness of at least 10 ⁇ m, from 10 to 100 ⁇ m, from 15 to 75 ⁇ m, or from 20 to 50 ⁇ m.
  • the electrolyte material has a thickness of at least 1 ⁇ m, from 1 to 30 ⁇ m, from 2 to 20 ⁇ m, or from 5 to 15 ⁇ m.
  • One or more embodiments generally relate to a method of producing hydrogen. Generally, the method comprises: providing the protonic ceramic electrochemical cell described herein; reacting water at the negative electrode to generate oxygen and protons; causing the protons to pass through the proton-conducting electrolyte to the positive electrode; and supplying an electrical current to the negative electrode and reducing at least a portion of the protons to form hydrogen.
  • One or more embodiments generally relate to a method of generating electricity.
  • the method comprises: providing the protonic ceramic electrochemical cell described herein; supplying hydrogen to the electrochemical cell and oxidizing the hydrogen at a first electrode to form protons and electrons; causing the protons to pass through the proton- conducting electrolyte to a second electrode; causing the electrons generated at the second electrode to induce an electrical current and passing the electrical current through an electrical load that is connected with the second electrode and the first electrode; and reacting the protons with oxygen at the second electrode to produce water.
  • FIG. 1 depicts an exemplary protonic ceramic electrochemical cell electrochemical cell comprising an electrode formed from the solid composite materials described herein; and [0014]
  • FIG. 2 depicts schematic illustrations of PCEC electrolytes fabricated using: (a) an ultrasonic spray coater and (b) a traditional air brush.
  • DETAILED DESCRIPTION [0015] A solid composite material has been developed that may be used for various applications, including forming electrodes in electrochemical cells.
  • the solid composite materials described herein may comprise a double perovskite phase and a single perovskite phase. Due to its unique chemical formulation, the solid composite material of the present disclosure may be used to produce electrodes and electrochemical cells that exhibit superior performance.
  • positive electrodes may be formed from the solid composite materials that can be used in protonic ceramic electrochemical cells (“PCECs”) and which exhibit superior performance. More particularly, it has been discovered that high-performance, low-temperature ( ⁇ 450°C) PCECs (“LT-PCECs”) may be produced using the solid composite materials described herein.
  • PCECs protonic ceramic electrochemical cells
  • LT-PCECs high-performance, low-temperature PCECs
  • a protonic ceramic electrochemical cell may be provided that comprises a positive electrode comprising a solid composite material according to any embodiment described herein.
  • the PCEC further comprises a negative electrode that comprises any material conventional for such electrodes, including, but not limited to, BCZYYb7111 and NiO. Additionally, the PCEC comprises an electrolyte located between the positive and negative electrodes.
  • the electrolyte can be any conventional electrolyte material, including, but not limited to BCZYYb4411.
  • the positive and negative electrodes have a thickness of at least 10 ⁇ m, from 10 to 100 ⁇ m, from 15 to 75 ⁇ m, or from 20 to 50 ⁇ m. Additionally, or in the alternative, the electrolyte material has a thickness of at least 1 ⁇ m, from 1 to 30 ⁇ m, from 2 to 20 ⁇ m, or from 5 to 15 ⁇ m.
  • the Solid Composite Materials [0017] According to various embodiments, a solid composite material may be produced that comprises a double perovskite phase and a single perovskite phase.
  • the double perovskite phase comprises PrBaSrCoFeO (“PBSCF”) and the single perovskite phase comprises BaSrCoO (“BSC”).
  • PBSCF PrBaSrCoFeO
  • BSC BaSrCoO
  • perovskite and single perovskite phase means any material with a crystal structure having the formula ABX3, wherein “A” and “B” refer to cations and “X” refers to an anion.
  • a “double perovskite” refers to a complex perovskite material with a crystal structure of AA’BB’X 6 , wherein “A” and “A’” represent two or more cations, such as cations of alkaline earth metals and/or rare earth metals; “B” and “B’” represent two or more cations, such as those containing a transition metal; and “X” represents at least one anion.
  • a double phase perovskite may have a unit cell that is twice that of a single perovskite phase, with two cations ordered on the “B” site.
  • the solid composite material such as the double perovskite phase and the single perovskite phase, may be synthesized using a wet- chemistry method, wherein two or more cations and one or more anions are dissolved in water in stoichiometric amounts.
  • Exemplary precursor reagents for the cations and/or anions may include, for example, Pr 6 O 11 , Ba(NO 3 ) 2 , Sr(NO 3 ) 2 , Co(NO 3 )•6H 2 O, Fe(NO 3 ) 3 •9H 2 O, and/or Fe(NO 3 ) 3 •6H 2 O.
  • Ba(NO 3 ) 2 , Sr(NO3)2, Co(NO3)3•6H2O, and Fe(NO3)3•6H2O (or Fe(NO3)3•9H2O) may be at least partially dissolved in deionized water in stoichiometric amounts to form an initial reaction solution.
  • a specific amount of Pr 6 O 11 may be dissolved in diluted nitric acid and subsequently added into the reaction solution.
  • a calculated amount of Pr6O11 may be dissolved in a about 20 weight percent diluted nitric acid solution at about 100°C to obtain the praseodymium nitrate solution.
  • the praseodymium nitrate solution may be added to the reaction solution under stirring for 10 to 60 minutes, 15 to 45 minutes, or about 30 minutes at temperatures in the range of about 15 to about 100 °C, about 20 to about 80 °C, or about 20 to about 50 °C.
  • the reaction solution comprises: (a) 0.05 to 0.5 moles, 0.1 to 0.4 moles, or 0.15 to 0.25 moles of Pr6O11; (b) 0.05 to 1.0 moles, 0.1 to 0.8, or 0.3 to 0.6 moles of Ba(NO3)2; (c) 0.05 to 1.0 moles, 0.1 to 0.8, or 0.3 to 0.6 moles of Sr(NO 3 ) 2 ; (d) 0.1 to 2.0 moles, 0.5 to 1.9 moles, or 1.0 to 1.7 moles of Co(NO3)3; and/or (e) 0.05 to 1.0 moles, 0.1 to 0.8, or 0.3 to 0.6 moles of Fe(NO3)3.
  • the reaction solution comprises about 0.17 moles of Pr6O11, about 0.5 moles of Ba(NO3)2, about 0.5 moles of Sr(NO3)2, about 1.5 moles of Co(NO3)3, and about 0.5 moles of Fe(NO3)3.
  • one or more complexing and chelating agents such as citric acid (“CA”) and/or ethylenediaminetetraacetic acid (“EDTA”), may be added to the reaction solution.
  • CA citric acid
  • EDTA ethylenediaminetetraacetic acid
  • the complexing and chelating agents may be added to the reaction solution under continuous stirring for 10 to 90 minutes, 15 to 75 minutes, or about 60 minutes at temperatures in the range of about 15 to about 100 °C, about 20 to about 80 °C, about 20 to about 50 °C, or about 23°C in order to obtain complete complexation.
  • the resulting reaction solution may have a CA:total cation molar ratio of at least 1:1, 1.5:1, or 2:1 and/or less than 4:1, 3.5:1, or 3:1.
  • the reaction solution may then be heated to thereby form a gel.
  • the reaction solution may be heated at a temperature in the range of about 200 to about 400 °C, about 225 to about 350 °C, or about 250 to about 300 °C.
  • the reaction solution may be heated using conventional equipment known in the art, such as via a hot plate or oven, until a gel is formed.
  • a dryer such as a drying oven
  • the dried and calcined powder may be sintered at a temperature in the range of about 500 to about 900 °C, about 600 to about 800 °C, or about 750 to about 775 °C until the dried and calcined powder has crystallized into the solid composite material comprising a double perovskite phase and a single perovskite phase.
  • the resulting solid composite material may be in the form of a powder.
  • the phase structures within the double perovskite phase and the single perovskite phase are such that each perovskite is a separately identifiable structure within the overall material with each phase having its own identifiable crystalline structure.
  • the double perovskite phase has a formula of Pr1.44Ba0.11Sr0.45Co1.32Fe0.68O6- ⁇ and the single perovskite phase has a formula of Ba0.62Sr0.38CoO3- ⁇ -.
  • the double perovskite phase has a formula of Pr 1.39 Ba 0.14 Sr 0.53 Co 1.48 Fe 0.76 O 6- ⁇ - and the single perovskite phase has a formula of Ba 0.66 Sr 0.34 CoO 3- ⁇ .
  • the double perovskite phase has a tetragonal (P4/mmm) crystal structure and/or the single perovskite phase has a hexagonal P63/mmc crystal structure, as confirmed by transmission electron microscopy (“TEM”) and X-ray diffraction (“XRD”).
  • TEM transmission electron microscopy
  • XRD X-ray diffraction
  • the crystal structure of the as-synthesized powders was measured using XRD (Rigaku MiniFlex diffractometer with a Cu K ⁇ radiation source operated at 30 kV and 15 mA). The scan speed was 1°/min.
  • the morphology, microstructure, and chemical composition of the solid composite materials were examined using transmission electron microscopy (TEM, FEI Tecnai Osiris 200 Kv S/TEM system and Talos F200X S/TEM system operated at 200 kV, equipped with an FEG (field emission gun) cathode and four in-column Super-X energy dispersive X-ray spectrometer (EDS) detectors with a total collection angle of 0.9 sr).
  • TEM transmission electron microscopy
  • FEG field emission gun
  • EDS super-X energy dispersive X-ray spectrometer
  • the solid composite material comprises at least 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 weight percent of the double perovskite phase. Additionally, or in the alternative, the solid composite material may comprise less than 99, 95, 90, 85, 80, or 75 weight percent of double perovskite phase. In certain embodiments, the solid composite material comprises about 70 weight percent of double perovskite phase. These weight percentages and those disclosed below may be confirmed by XRD. [0041] In one or more embodiments, the solid composite material comprises at least 1, 5, 10, 15, 20, or 25 weight percent of the single perovskite phase.
  • the solid composite material may comprise less than 60, 50, 45, 40, or 35 weight percent of single perovskite phase. In certain embodiments, the solid composite material comprises about 30 weight percent of single perovskite phase.
  • the solid composite material may have an average particle size of at least 1, 5, 10, 15, or 20 nm and/or less than 100, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, or 40 nm, as confirmed by TEM.
  • the Protonic Ceramic Electrochemical Cells [0043] The solid composite materials described herein may be used in a variety of applications.
  • PCEC protonic ceramic electrochemical cells
  • the method comprises: (a) forming a single-layer or double-layer negative electrode 12 on a temporary substrate; (b) forming an electrolyte 14 on the negative electrode 12 to thereby form a stack; (c) optionally sintering the stack to form a portion of the electrochemical cell 10; and (d) forming a positive electrode 16 on the electrolyte 14, thereby forming a second stack comprising the negative electrode 12, the electrolyte 14, and the positive electrode 16; and (f) optionally sintering the second stack to form the electrochemical cell 10.
  • the electrochemical cell 10 comprises a negative electrode 12.
  • the negative electrode 12 can function as an anode or cathode in the cell 10. Particularly, when the cell 10 is operated in a hydrogen-producing mode, the negative electrode 12 (functioning as a cathode) reduces protons to hydrogen, and when the cell is operated in an electricity-producing mode, the first electrode (functioning as an anode) forms protons from hydrogen.
  • the negative electrode 12 comprises any conventional and commercially-available electrode material currently available.
  • the negative electrode 12 comprises and may be formed from BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3- ⁇ (“BCZYYb7111”).
  • the negative electrode 12 comprises at least 50, 75, 90, or 99 weight percent of BCZYYb7111.
  • negative electrode powder may be composed of BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3- ⁇ (“BCZYYb7111”), NiO, and corn starch with a weight ratio of 2:3:1. It has been widely recognized that an additional Ba reservoir can facilitate electrolyte densification and mitigate elemental segregation, which consequently improves proton conductivity. Thus, an anode substrate with minimized Ba nonstoichiometry (i.e., low Ba deficiency) can promote electrolyte densification and proton conduction.
  • BCZYYb7111 may be synthesized via a fast-heating solid-state sintering (“SSS”) method.
  • SSS solid-state sintering
  • a stoichiometric amount of BaCO3, CeO2, ZrO2, Y2O3, Yb2O3, and about one weight percent of NiO may be first ball-milled for about 48 hours.
  • the homogeneous mixture may be calcined at 1,350°C with a fast-heating rate of 10°C/min for 5 hours in the air to crystallize BCZYYb7111, which reduces Ba vaporization during the anode powder crystallization process and thereby maintains the Ba stoichiometry.
  • the obtained chuck powder may then be crushed into a fine powder and then ball-milled again and dried at 120°C overnight.
  • the as-synthesized BCZYYb7111 fine powder may then be ball- milled with NiO and corn starch for 48 hours. After drying at 120°C, a negative electrode powder with a low Ba deficiency may be synthesized.
  • the anode substrate with a low Ba deficiency may function as the Ba reservoir to assist in electrolyte densification and retain chemical homogeneity.
  • the negative electrode functional layer powder may be composed of at least 20, 30, or 40 weight percent and/or less than 80, 70, 60, or 50 weight percent of BaCe0.7Zr0.1Y0.1Yb0.1O3- ⁇ (BCZYYb7111) and at least 20, 30, 40, 50, or 60 weight percent and/or less than 95, 80, 70, or 65 weight percent of NiO.
  • the addition of corn starch to the powder may be optional.
  • the negative electrode powder may be mixed with various additives (e.g., menhaden fish oil, b-98 polyvinyl butyral, polyethylene glycol 400, cyclohexanone, di-n-butyl phthalate, and/or xylenes) and an alcohol (e.g., ethanol) and then ball- milled for a duration (e.g., 24 hours) to obtain a negative electrode slurry.
  • the negative electrode slurry may be coated on desired substrate (e.g., Mylar) via tape-casting to form a negative electrode function layer.
  • the negative electrode slurry may then be cast on the negative electrode function layer.
  • the resulting two layers may be dried (e.g., in air for 48 hours) and then presintered at about 800°C for about 30 minutes to thermally degrade all the organic materials.
  • the negative electrode 12 may have a thickness in a range of about 10 ⁇ m to about 70 ⁇ m, about 20 ⁇ m to about 60 ⁇ m, about 30 ⁇ m to about 50 ⁇ m, or about 40 ⁇ m.
  • the electrochemical cell 10 comprises a proton- conducting electrolyte layer 14.
  • the proton-conducting electrolyte layer 14 may be formed from any known or conventional electrolyte material currently available. In certain embodiments, the proton-conducting electrolyte layer 14 may be formed from BaCe0.4Zr0.4Y0.1Yb0.1O3- ⁇ (“BCZYYb4411”). [0056] In one or more embodiments, the electrolyte powder used to form the electrolyte layer 14 may be prepared using a wet-chemistry method to obtain nanosized electrolyte powder.
  • BaCe0.4Zr0.4Y0.1Yb0.1O3- ⁇ (BCZYYb4411) may be synthesized via a wet-chemistry method using Y2O3, Yb2O3, Ba(NO3)2, Ce(NO3)3•6H2O, and zirconyl nitrate solution (35 wt. % in diluted nitric acid) as the precursors.
  • the calculated amounts of Y 2 O 3 and Yb 2 O 3 may be first dissolved in 20 weight percent diluted nitric acid solution at 100°C to obtain yttrium and ytterbium nitrate solutions.
  • stoichiometric amounts of Ba(NO3)2, Ce(NO3)3•6H2O, and zirconyl nitrate may be subsequently added into the yttrium and ytterbium nitrate solution, and then stirred for 30 minutes.
  • the complexing and chelating agents, citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) may then be added to the above solution with a CA:EDTA:total cation molar ratio of 2:2:1, which may be continuously stirred for 1 hour at room temperature for complete complexation.
  • the pH may then be adjusted to ⁇ 9 by adding an aqueous NH4OH solution.
  • the BCZYYb4411 electrolyte powder may be mixed with 1 wt.% NiO (NiO functions as the sintering aid, the amount of which is based on the mass of BCZYYb4411) and binders (e.g., fish oil, b-98 polyvinyl butyral, di-n-butyl phthalate, and ethanol).
  • NiO functions as the sintering aid, the amount of which is based on the mass of BCZYYb4411
  • binders e.g., fish oil, b-98 polyvinyl butyral, di-n-butyl phthalate, and ethanol.
  • the electrolyte powder may be mixed with a specific amount of fish oil, b-98 polyvinyl butyral, di-n-butyl phthalate, and ethanol to prepare well-dispersed ink. To further improve its dispersion, the ink should be ball milled for four days.
  • the particle size distribution of the electrolyte powder in the ink may be evaluated using a Malvern Zetasizer Nano S. To ensure the reliability of these results, three measurements may be conducted. The obtained data may be analyzed utilizing the Mie theory. In certain embodiments, approximately 10 vol.% of the powder exhibits a particle size of ⁇ 150 nm, while the majority of the powder exhibits a particle size of ⁇ 500 nm.
  • the average particle size may be 360 to 375 nm.
  • An electrolyte powder with a small particle size may be essential for achieving an ultrathin and uniform electrolyte layer.
  • an ultrasonic coating system may be used to fabricate the ultrathin (quasi-two dimensional), chemically homogeneous, and robust proton- conducting electrolyte layer 14.
  • at least a portion of the electrolyte ink may be loaded into an ultrasonic syringe.
  • the flow rate of the electrolyte ink fed to the ultrasonic nozzle may be controlled using a syringe pump.
  • An ultrasonic nozzle installed on the x-y-z robotic arm may be used for coating the ultrathin electrolyte layer.
  • the coating time, spray spot size, coating speed, ultrasonic power, and substrate temperature may be optimized to achieve the desired electrolyte thickness and density.
  • the obtained electrolyte layer 14 applied on the negative electrode layer 12 may be co-sintered at about 1,450°C for about 5 hours to fabricate the PCEC half-cells.
  • the ink may be loaded in an ultrasonic reservoir.
  • the ultrasonic nozzle creates highly dispersed droplets, which allows the fabrication of uniform and ultrathin proton-conducting electrolyte.
  • the negative substrate is also important for high-quality electrolyte.
  • anode substrates with a two-layers structure may be utilized.
  • the electrolyte ink was coated on the negative electrode functional layer.
  • This negative electrode functional layer may not contain any pore former, which exhibits low porosity, creating a surface with high flatness.
  • This smooth negative functional layer is one of the main factors for fabricating thin, uniform, and dense electrolyte.
  • the porous negative electrode layer can increase the active surface area and ensure fast mass transport.
  • LT-PCECs with ultrathin, bamboo-structured (single- grain thick), and chemically homogeneous electrolytes may be fabricated via a scalable and cost- effective ultrasonic spray-coating process, which may minimize the resistance of proton conduction across the grain boundary, as shown in FIG. 2. More particularly, as shown in FIG. 2, schematic illustrations are provided of PCEC electrolytes fabricated using: (a) an ultrasonic spray coater and (b) a traditional air brush. The ultrasonic spray coating may yield an ultrathin, bamboo-structured (single-grain thick), and chemically homogeneous electrolyte with a larger grain size and less grain boundary.
  • the traditional air brush method may lead to a thin, multiple-grains thick electrolyte with a smaller grain size and more grain boundaries. Consequently, the grain boundary has a much lower proton conductivity than the grain interior.
  • the arrows in FIG. 2 show that proton conduction encounters high resistance at the grain boundaries; thus, the electrolyte prepared via the ultrasonic spray coating has a higher proton conductivity.
  • ASR o area-specific ohmic resistance
  • Poor sinterability and Ba evaporation are two main challenges associated with proton-conducting electrolyte fabrications.
  • the conductivity of the electrolytes was measured by using the EIS and a comprehensive analysis of the EIS spectra was performed to determine the grain bulk and grain boundary conductivity.
  • the electrolyte powder was subjected to uniaxial dry pressing to form a 20 mm diameter pellet at a pressure of 150 bar, which was then sintered for 5 hours at 1450°C.
  • the resulting pellet was polished with sandpaper to attain a flat surface with a thickness of ⁇ 1 mm.
  • Platinum (Pt) paste was applied on both sides of the pellet (with an effective area of 0.5 cm 2 ) as the current collector via brush painting, which was then calcined at 350°C for 30 minutes.
  • the ohmic resistance of this BCZYYb4411 electrolyte pellets was measured by performing EIS under a humidified argon atmosphere (3% steam) from 500 to 250 °C. Before each measurement, the pellet was held at each temperature for approximately one hour to achieve a steady state. [0064] The EIS spectra were collected using a Gamry 1010 interface. The obtained impedance spectra were then analyzed using Zview software to separate and analyze the bulk and grain boundary resistances. The “brick layer model” was used to calculate the bulk and grain boundary conductivities. [0065] Due to the ultrasonic spray coating method, the electrolyte layer may be dense, with a uniform thickness.
  • the electrolyte surface has an average grain size that is larger than the electrolyte thickness. Therefore, in such embodiments, the PCEC obtained via this process has a quasi-2D electrolyte, which exhibits a low grain boundary area and reduced ASRO.
  • the ultrathin electrolyte layer 14 may exhibit a bamboo structure where the grain boundaries appear perpendicular to the negative electrode 12.
  • the thin electrolyte layer 14 may be chemically homogeneous and also show a homogeneous elemental distribution, implying that the chemical composition is consistent throughout the electrolyte. Element segregation at the grain boundary can lead to a positive potential, which decreases proton conduction. Consequently, the PCECs fabricated in accordance with the present disclosure may achieve an ASR O that is lower or comparable to that of PCECs fabricated via costly and complicated prior art techniques. [0067] In one or more embodiments, the proton-conducting electrolyte layer 14 has an average grain size of at least 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or 7 ⁇ m.
  • the proton-conducting electrolyte layer 18 has an average grain size less than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, or 3 ⁇ m. This smaller grain size may be derived from the ultrasonic spray coating methodology. It has also been observed that PCEC’s fabricated using ultrasonic spray coating, rather than traditional air brushing, may exhibit reduced ASRO, indicating that the electrolyte with a bigger grain size and fewer grain boundaries has a higher proton conductivity.
  • the proton-conducting electryolyte 14 may have a thickness in a range of about 0.01 ⁇ m to about 75 ⁇ m, about 1 ⁇ m to about 25 ⁇ m, about 5 ⁇ m to about 15 ⁇ m, or about 10 ⁇ m.
  • the electrochemical cell 10 comprises a positive electrode 16. It will be appreciated that, although it is referred to as a “positive electrode,” depending on the operating mode employed, the positive electrode 16 can function as an anode or cathode.
  • the positive electrode 16 when the cell 10 is operated in hydrogen-producing mode, the positive electrode 16 (functioning as an anode) forms protons and oxygen from water using an electrical current, and when the cell 10 is operated in electricity-producing mode, the positive electrode 16 (functioning as a cathode) reacts protons and electrons with oxygen to form water.
  • the positive electrode 16 comprises, consists essentially of, or consists of the solid composite materials described herein. In one or more embodiments, the positive electrode 16 comprises at least 50, 75, 90, 95, or 99 weight percent of the solid composite materials.
  • An objective of the present disclosure was to reduce the ASRP of the PCEC to less than 0.4 ⁇ cm 2 at 450°C, which would further improve the PCEC performance at less than 450°C.
  • an in-situ formed composite positive electrode was developed that was composed of the solid composite materials described herein. More particularly, a positive electrode was developed with double perovskite phase and single perovskite phase nanoparticles to reduce the ASR P .
  • the in-situ formed positive electrode powder was synthesized via the above-referenced wet-chemistry method described above for producing the solid composite materials described herein.
  • stoichiometric amounts of Pr 6 O 11 , Ba(NO 3 ) 2 , Sr(NO 3 ) 2 , Co(NO 3 ) 2 •6H 2 O, and Fe(NO 3 ) 3 •9H 2 O may be utilized as the precursors.
  • a calculated amount of Pr6O11 may be first dissolved in 20 weight percent diluted nitric acid solution at 100°C to obtain a praseodymium nitrate solution.
  • stoichiometric amounts of Ba(NO 3 ) 2 , Sr(NO 3 ) 2 , Co(NO3)2•6H2O, and Fe(NO3)3•9H2O may be subsequently added into the praseodymium nitrate solution, and then stirred for 30 minutes.
  • the complexing and chelating agents, citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) may then be added to the above solution with a CA:EDTA:total cation molar ratio of 2:2:1, and then continuously stirred for 1 hour at room temperature for complete complexation.
  • the pH may be adjusted to ⁇ 9 by adding an aqueous NH4OH solution.
  • the solution may then be heated at 250°C until a gel is formed.
  • the gel may be immediately placed in a drying oven at 175°C for 24 hours.
  • the obtained black powder may then be calcined under air at 600°C for 5 hours, followed by ball-milling in ethanol for 1 day and then drying at 100°C. Upon sintering at 765°C, the calcined powder will be crystallized to form the solid composite materials powder.
  • a designated amount (e.g., 5 grams) of the solid composite materials powder may be dispersed in a dispersant (e.g., one gram of 20 weight percent solsperse 28000 (Lubrizol) dissolved in ⁇ -terpinol), and a binder (e.g., 0.5 grams of 5 weight percent V-006 (Heraeus) dissolved in ⁇ -terpinol) and then mixed and ground to thereby form a positive electrode slurry.
  • a dispersant e.g., one gram of 20 weight percent solsperse 28000 (Lubrizol) dissolved in ⁇ -terpinol
  • a binder e.g., 0.5 grams of 5 weight percent V-006 (Heraeus) dissolved in ⁇ -terpinol
  • the resulting slurry may be applied using conventional application methods, such as ultrasonic spray coating, to the electrolyte layer 14 in order to form the positive electrode layer 16.
  • the positive electrode slurry may be brush painted on the electrolyte layer 14, and the PCEC single-cell may then be directly sealed on an alumina tube without presintering the positive electrode.
  • the positive electrode 16 may have a thickness in a range of about 10 ⁇ m to about 70 ⁇ m, about 20 ⁇ m to about 60 ⁇ m, about 20 ⁇ m to about 50 ⁇ m, or about 30 ⁇ m.
  • the positive electrodes formed from the solid composite materials may exhibit an area-specific electrode polarization resistance (“ASR P ”) at 400°C of at least 0.1, 0.5, 1.0, or 1.2 ⁇ cm 2 and/or less than 9, 8, 7, 6, 5, 4, 3, 2, or 1.5 ⁇ cm 2 . Additionally, or in the alternative, the positive electrodes formed from the solid composite materials may exhibit an ASR P at 450°C of at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7 ⁇ cm 2 and/or less than 4, 3, 2, or 1 ⁇ cm 2 .
  • ASR P area-specific electrode polarization resistance
  • the positive electrodes formed from the solid composite materials may exhibit an ASRP at 500°C of at least 0.05, 0.1, or 0.15 ⁇ cm 2 and/or less than 1, 0.9, 0.8, 0.7, or 0.6 ⁇ cm 2 . Additionally, or in the alternative, the positive electrodes formed from the solid composite materials may exhibit an ASR P at 550°C of at least 0.01, 0.05, or 0.1 ⁇ cm 2 and/or less than 1, 0.9, 0.8, 0.7, 0.6, 0.5, or 0.4 ⁇ cm 2 .
  • the positive electrodes formed from the solid composite materials may exhibit an ASRP at 600°C of at least 0.01 or 0.05 ⁇ cm 2 and/or less than 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, or 0.3 ⁇ cm 2 .
  • the positive electrodes formed from the solid composite materials may exhibit an activation energy of at least 10, 25, 50, 75, 80, or 85 kJ/mol and/or less than 150, 130, 110, 105, or 100 kg/mol. This indicates that the positive electrodes described herein can function as a promising positive electrode at lower operating temperatures.
  • the positive electrodes formed from the solid composite materials may exhibit oxygen temperature-programmed desorption (O 2 -TPD) with: (a) one peak at a temperature of at least 200°C, 215°C, or 230°C and/or less than 320°C, 310°C, 300°C, 290°C, 280°C, 270°C, or 260°C and (b) a second peak at a temperature of at least 200°C, 225°C, 250°C, 275°C, or 290°C and/or less than 380°C, 370°C, 360°C, 350°C, 340°C, 330°C, 320°C, 310°C, or 300°C.
  • O 2 -TPD oxygen temperature-programmed desorption
  • the positive electrodes formed from the solid composite materials may exhibit bulk oxygen-ion diffusion coefficients (“Dchem”) of at least 10 -7 or 10 -6 cm 2 s -1 and/or less than 10 -4 cm 2 s -1 at 500°C or 550°C. It has been observed that the inventive electrodes have higher bulk oxygen-ion diffusion coefficients (Dchem) than prior art electrodes, suggesting that the inventive electrodes exhibit enhanced oxygen-ion diffusion in the bulk.
  • Dchem bulk oxygen-ion diffusion coefficients
  • a bar was prepared using a high-precision diamond saw. ECR measurement was conducted at 700°C, 650°C, 600°C, 550°C, and 500°C. At each temperature, the oxygen concentration was initially set as 2 vol.% (10 sccm O2 + 490 sccm Ar). ECR was measured via a four-probe method with a current of 40 mA applied and voltage measured. Once the voltage reached equilibrium, the oxygen concentration was immediately changed from 2 volume percent to 20 volume percent. The voltage response was recorded. The relative conductivity change data was calculated using the NETL ECR analysis tool, which determines the surface exchange coefficient (kchem) and bulk diffusion coefficient (Dchem).
  • the positive electrodes formed from the solid composite materials may exhibit a surface oxygen exchange coefficient (k chem ) of at least 10 -5 or 10 -4 cm s -1 and/or less than 10 -3 cm s -1 at 500°C or 550°C. It has been observed that the inventive electrodes exhibit higher surface oxygen exchange coefficients (kchem) relative to prior art electrodes formed from just double phase perovskites. For example, at 550°C, the kchem of inventive electrodes may be more than twice than that of prior art electrodes formed from just a double perovskite phase, implying that the single perovskite phase is beneficial for accelerating the surface oxygen exchange kinetics.
  • k chem surface oxygen exchange coefficient
  • the positive electrodes formed from the solid composite materials may exhibit an activation energy associated with Dchem of at least 50, 75, or 100 kJ/mol and/or less than 175, 150, or 125 kJ/mol.
  • the positive electrodes formed from the solid composite materials may exhibit an activation energy associated with k chem of at least 20, 40, or 60 kJ/mol and/or less than 100, 90, 80, or 70 kJ/mol. Both of these activation energies were observed to be lower than those of the prior art electrodes formed from just a double perovskite phase, further highlighting promising performance at lowered operating temperatures.
  • the inventive positive electrodes formed from the solid composite materials may reduce the ASRp by a factor of five relative to prior art electrodes.
  • the distribution of relaxation time (“DRT”) analysis may be provided by graph plots (as defined by the graph peaks) divided into three main regions, i.e., a low-frequency region ( ⁇ 100 Hz), an intermediate-frequency region (100-10,000 Hz), and a high-frequency region (>10,000 Hz), which correspond to oxygen mass transport, oxygen exchange on the positive electrode, and the charge transfer process, respectively.
  • the positive electrodes formed from the solid composite materials may exhibit a DRT in a low- frequency region at 450°C of at least 0.01 and/or less than 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, or 0.2 ⁇ /cm 2 .
  • the positive electrodes formed from the solid composite materials may exhibit a DRT in an intermediate-frequency region at 450°C of at least 0.01 and/or less than 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, or 0.2 ⁇ /cm 2 . Additionally, or in the alternative, the positive electrodes formed from the solid composite materials may exhibit a DRT in a high-frequency region at 450°C of at least 0.01 and/or less than 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 ⁇ /cm 2 .
  • the inventive electrodes may exhibit lower DRT peaks at low and medium frequencies relative to prior art electrodes formed from just a double perovskite phase, indicating that the inventive electrodes exhibit enhanced surface oxygen exchange kinetics, which may be attributed to the porous structure of the inventive electrode.
  • the positive electrodes formed from the solid composite materials may have a BET-measured surface area of at least 5, 6, 7, 8, or 9 m 2 /g and/or less than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10 m 2 /g.
  • Nitrogen Brunauer–Emmett– Teller (BET) surface area analysis and O 2 -temperature-programmed desorption (O 2 -TPD) may be conducted using a ChemBET Pulsar chemisorption analyzer.
  • BET Brunauer–Emmett– Teller
  • O 2 -TPD O 2 -temperature-programmed desorption
  • the inventive solid composite materials display a superior ORR performance owing to the higher oxygen diffusivity of the combined double perovskite phase and single perovskite phase. It was observed that the energy barriers (Ea,bulk) exhibit a decreasing order of the inventive single perovskite phase (BSC) (2.12 eV) > the prior art double perovskite phase (PBSCF-1) (0.88 eV) > the inventive double perovskite phase (PBSCF-2) (0.51 eV).
  • BSC inventive single perovskite phase
  • PBSCF-1 prior art double perovskite phase
  • PBSCF-2 inventive double perovskite phase
  • the E a , bulk in the inventive double perovskite phase is 0.37 eV lower than in the prior art double perovskite phase.
  • the energy differences will have a meaningful impact on atomic oxygen diffusion and correlate very well with the measured diffusivities.
  • the climbing image-nudged elastic band (CI-NEB) and the dimer methods were employed to model oxygen diffusion in bulk lattices.
  • the two vacancy sites with the lowest formation energies (Ov1 and Ov2) were marked.
  • the structure with the most stable oxygen vacancy (“Ov1”) is considered the initial state (“IS”) for lattice oxygen diffusions, whereas the structure with the most stable nearest oxygen vacancy is determined as the final state (“FS”).
  • the diffusion pathways in the double perovskite phases cross the “critical triangle” formed by one Co atom at the B site and two Pr atoms at the A sites, as described by Mastrikov.
  • the observed surface exchange rates may also be observed using DFT analysis. It was observed that the oxygen surface exchange coefficient (kchem) varies linearly against the bulk oxygen vacancy formation energy ( ⁇ E Ov ). Furthermore, a lower ⁇ E Ov would indicate a higher kchem. As such, the high kchem observed in the single perovskite phase (BSC) can also be successfully explained based on the trends in the calculated oxygen vacancy formation energies.
  • PCECs containing a positive electrode formed from the solid composite materials described herein may exhibit an ASR O at 400°C of at least 0.01 ⁇ cm 2 and less than 0.5, 0.4, or 0.3 ⁇ cm 2 . Additionally, or in the alternative, PCECs containing a positive electrode formed from the solid composite materials described herein may exhibit an ASR O at 450°C of at least 0.01 ⁇ cm 2 and less than 0.4, 0.3, or 0.25 ⁇ cm 2 . Additionally, or in the alternative, PCECs containing a positive electrode formed from the solid composite materials described herein may exhibit an ASRO at 500°C of at least 0.01 ⁇ cm 2 and less than 0.4, 0.3, 0.25, or 0.2 ⁇ cm 2 .
  • the inventive positive electrodes formed from the solid composite materials described herein may exhibit an average peeling strength of at least 4, 5, 6, 7, 8, or 9 N and/or less than 20, 15, or 14 N over a time period of 2, 3, 4, 5, or 6 minutes. [00105] It was observed that the inventive positive electrode may exhibit an average peeling strength of 6.8 N, 42% higher than that of the prior art positive electrode (4.8 N). Therefore, the inventive positive electrode simultaneously improved the electrochemical performance and reduced the ohmic resistance at lower operating temperatures. [00106] The peeling strength of the positive electrodes was measured according to the ASTM D903 180-degree peeling strength testing standard. Briefly, the specimen was placed in the peeling strength test machine by fixing the negative electrode using heavy-duty double-sided tape.
  • this positive electrode may simultaneously facilitate the surface oxygen exchange and bulk oxygen-ion diffusion, particularly at low operating temperatures, which can significantly decrease the ASR P , thereby allowing an extraordinarily low ASR P (e.g., about 0.38 ⁇ cm 2 ) to be achieved at 450°C (versus the 0.76 ⁇ cm 2 ASRP of the prior art positive electrode).
  • an extraordinarily low ASR P e.g., about 0.38 ⁇ cm 2
  • the LT-PCECs equipped with low-resistance electrolytes and the positive electrodes described herein may exhibit remarkable performance at ⁇ 450°C, as demonstrated by the peak power density. For example, at 400°C, a fuel cell PPD of about 0.34 W cm -2 may be achieved using H2, which doubles the PPD of the prior art PCECs.
  • the inventive LT-PCECs can exhibit a peak power density (with air, ammonia, hydrogen, and/or oxygen fed to the positive electrode and/or the negative electrode) of at least 0.01, 0.05, or 0.1 W/cm 2 and/or less than 1.8, 1, 0.5, 0.4, or 0.3 W/cm 2 at 275°C, 300°C, or 350°C.
  • the inventive LT-PCECs when the inventive LT-PCEC operated at 275°C, it may function as a practical fuel cell PPD of about 0.1 W cm -2 on H 2 -O 2 .
  • the LT-PCECs operating at ⁇ 450°C may also provide good fuel flexibility.
  • the inventive LT-PCECs achieved PPDs of about 0.65 W/cm 2 at 500°C, about 0.28 W/cm 2 at 450°C, and about 0.16 W/cm 2 at temperatures as low as 400°C.
  • the direct-ammonia PCECs may also exhibit outstanding performance at 500-600°C, achieving a PPD of about 1.38 W/cm 2 at 600°C, which well exceeds the results reported in the literature.
  • a PPD about 1.38 W/cm 2 at 600°C
  • the PCEC performance on ammonia was comparable to that on H 2 , indicating that the negative electrode was active for ammonia cracking, which suggested that ammonia can serve as a H2 carrier for power generation in PCECs.
  • the CH 4 conversion achieved over Sm0.2Ce0.7Ni0.1Ru0.05O2 reached ⁇ 27%, suggesting that the PCEC equipped with this catalyst can deliver viable power density.
  • the SDC-Ni- Ru ink was brush-painted on the negative electrode as a catalytic reforming layer. A mixture of methane with steam at a methane-to-steam ratio of 1:1 was fed to the negative electrode.
  • the CH4 flow rate which was set as 16 sccm at 500°C, 12 sccm at 450°C, and 8 sccm at 400°C, was also varied with the operating temperatures.
  • the hydrogen production of the inventive LT-PCECs may be evaluated in electrolysis mode at ⁇ 450°C.
  • a mixture of steam and nitrogen was supplied to the positive electrode with a steam concentration of 40%.
  • the steam concentration was controlled by bubbling nitrogen (100 sccm) through a customized temperature-controlled bubbler.
  • Pure hydrogen gas (15 sccm) was fed to the negative electrode as the sweep gas.
  • FE Faradaic efficiency
  • the negative electrode outlet gas was mixed with a nitrogen gas stream, which was then injected into an online gas chromatograph (INFICON 3000 Micro GC) to quantify the hydrogen production rate. This method allowed us to evaluate the PCEC electrolysis performance under realistic conditions and accurately determine the FE.
  • the inventive LT-PCECs in electrolysis mode may exhibit a current density of at least -1.0, -0.9, or -0.8 A cm -2 and/or less than -0.5, -0.6, or -0.7 A cm -2 at 1.4 V and 400°C. Additionally, or in the alternative, the inventive LT-PCECs in electrolysis mode may exhibit a current density of at least -0.01, -0.02, or -0.03 A cm -2 and/or less than -0.5, -0.6, or -0.7 A cm -2 at 1.4 V and 350°C.
  • the inventive PCECs can attain a current density of about -1.28 A cm -2 at 1.4 V and 450°C versus, e.g., 1.04 A cm -2 at 450°C for the prior art PCECs.
  • the inventive LT-PCECs in electrolysis mode may exhibit a Faradaic efficiency (“FE”) of at least 70, 75, 80, 85, 90, or 95 percent at 400°C and a current density of 0.4, 0.6, or 0.8 A cm -2 .
  • FE Faradaic efficiency
  • the cell-level electrical energy-to-chemical energy conversion efficiency of the inventive LT-PCECs may reach at least 77 percent, validating the feasibility of producing hydrogen with the inventive PCECs at ⁇ 450°C.
  • a relatively low FE (%) of PCECs may be one of the main challenges.
  • the low FE (%) is typically ascribed to the p-type electronic leakage across the electrolyte.
  • the p-type electronic leakage is due to the oxidation reaction ( ).
  • an electrolyte which suppresses the oxidation and favors hydration, could be developed to enhance the FE (%).
  • PCEC stability testing was also evaluated for power generation and hydrogen production at ⁇ 450°C.
  • the inventive LT-PCEC may continuously operate in fuel cell mode for at least 100 hours, achieving a degradation rate of less than 0.07 mV/h. After this time, there can be no observable change in the microstructure and no electrolyte cracking. The positive electrode-electrolyte interfaces may show no delamination, suggesting that the interfacial bonding is good and the thermal expansions are compatible.
  • the inventive LT-PCECs also exhibited superior long-term stability in electrolysis mode at 400°C.
  • the inventive PCECs when operated at a current density of -0.6 A cm -2 for at least 250 hours, may achieve a low degradation in the applied voltage (less than 0.15 mV/h) and FE.
  • the durability of the inventive LT-PCECs allows for H2 production with PCECs at 400°C for the first time, which dramatically reduces the required operating temperature and exceeds previous PCEC performance.
  • the stable terminal voltage and FE of the inventive PCECs suggest no noticeable degradation.
  • postmortem microstructural analysis of the inventive PCECs shows no evidence of degradation after the aforementioned long-term durability testing parameters.
  • the PCEC electrolyte fabricated via the simple and scalable process may exhibit a resistance comparable to or lower than that of PCECs prepared via costly and complicated processes.
  • the in-situ formed positive electrodes formed the solid composite materials described herein may exhibit a significantly improved electrocatalytic activity and reduced positive electrode-electrolyte contact resistance.
  • the inventive PCECs exhibited exceptional performance in both fuel cell and steam electrolysis modes.
  • the inventive PCECs may exhibit long-term durable fuel cell performance and remarkable durability in electrolysis mode at 400°C.
  • the protonic ceramic electrochemical cell 10 can produce hydrogen or generate electricity.
  • the protonic ceramic electrochemical cell 10 operates in a hydrogen-producing configuration. While in this configuration, water, preferably in the form of steam, is reacted at the negative electrode 12 to generate oxygen, electrons, and protons via an oxygen evolution reaction, which occurs at a temperature of from about 300°C to about 700°C. The generated protons may then pass through the proton-conducting electrolyte 14 to the positive electrode 16. Simultaneously, an electric current may be supplied to the positive electrode 16 from an external source, such as a solar panel.
  • an external source such as a solar panel.
  • the positive electrode 16 may reduce at least a portion of the protons to form hydrogen via a hydrogen evolution reaction, which occurs at a temperature of from about 300°C to about 700°C.
  • the protonic ceramic electrochemical cell 10 operates in an electricity-producing configuration. In this configuration, hydrogen is supplied to the cell 10, which is oxidized at the negative electrode 12 to generate electrons and protons via a hydrogen oxidation reaction occurring at a temperature of from about 300°C to about 700°C. In most embodiments, the supplied hydrogen is hydrogen previously formed while the cell 10 operated in the hydrogen-producing configuration.
  • the protons pass through the proton- conducting electrolyte 14 to the positive electrode 16 and react with oxygen to produce water via an oxygen reduction reaction, which occurs at a temperature of from about 300°C to about 700°C.
  • the generated electrons induce an electrical current and pass the electrical current through an electrical load to the positive electrode 16.
  • the electrical load is connected with the negative electrode 12 and positive electrode 16.
  • the electrons induce an open circuit voltage of the cell of from about 0.5 V to about 1.50 V, about 0.75 V to about 1.25 V, about 1.0 V to about 1.1 V, or about 1.05 V.
  • the present disclosure is also concerned with a method of producing hydrogen.
  • the method comprises providing a protonic ceramic electrochemical cell; reacting water at the negative electrode to generate oxygen and protons; causing the protons to pass through the electrolyte to the positive electrode; and supplying an electrical current to the negative electrode and reducing at least a portion of the protons to form hydrogen.
  • the protonic ceramic electrochemical cell 10 operates at a temperature of from about 200°C to about 1000°C, about 350°C to about 850°C, about 400°C to about 700°C, less than 450°C, or less than 400°C.
  • the present disclosure is also concerned with a method of generating electricity.
  • the method comprises: (a) providing a protonic ceramic electrochemical cell; (b) supplying hydrogen to the electrochemical cell and oxidizing the hydrogen at the negative electrode 12 to form protons and electrons; (c) causing the protons to pass through the electrolyte layer 14 to the positive electrode 16; (d) causing the electrons generated at the negative electrode 12 to induce an electrical current and passing the electrical current through an electrical load that is connected with the negative electrode 12 and the positive electrode 16; and (e) reacting the protons with oxygen at the positive electrode 16 to produce water.
  • DEFINITIONS [00142] It should be understood that the following is not intended to be an exclusive list of defined terms.
  • the terms “a,” “an,” and “the” mean one or more.
  • the term “about” refers to a range within ⁇ 10% of the stated value. For example, “about 10” would cover a range of 9 to 11.
  • the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed.
  • compositions can contain A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.
  • the terms “comprising,” “comprises,” and “comprise” are open- ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.
  • the terms “having,” “has,” and “have” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.
  • the terms “including,” “include,” and “included” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.
  • NUMERICAL RANGES [00149] The present description uses numerical ranges to quantify certain parameters relating to the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range.
  • a disclosed numerical range of 10 to 100 provides literal support for a claim reciting “greater than 10” (with no upper bounds) and a claim reciting “less than 100” (with no lower bounds).
  • CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS [00150]
  • the preferred forms of the invention described above are to be used as illustration only, and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.

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Abstract

L'invention concerne des piles électrochimiques céramiques protoniques (PCEC) qui peuvent être employées pour la génération d'énergie et la production d'hydrogène durable. Le fait de parvenir à une efficacité énergétique élevée et une durabilité à long terme à de faibles températures de fonctionnement est un défi de longue date dans la recherche sur les PCEC. L'invention concerne une approche simple et évolutive pour la fabrication d'électrolytes conducteurs de protons ultraminces, chimiquement homogènes et robustes et qui démontre une électrode positive composite formée in situ, Bao.62Sr0.38Co03-8-Pr1.44Bao.11Sro.45Co1.32Feo.6s06-6, qui réduit significativement la résistance ohmique, la résistance de contact électrode positive-électrolyte et la résistance de polarisation d'électrode. Les PCECs atteignent des densités de puissance élevées en mode pile à combustible et des densités de courant exceptionnelles en mode d'électrolyse de vapeur.
PCT/US2024/045358 2023-09-06 2024-09-05 Piles électrochimiques céramiques protoniques ayant une électrode positive composite Pending WO2025054305A1 (fr)

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US63/580,917 2023-09-06
US202363598327P 2023-11-13 2023-11-13
US63/598,327 2023-11-13

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108091885A (zh) * 2016-11-21 2018-05-29 中国科学院大连化学物理研究所 一种高温燃料电池阴极及其应用
CN110970148A (zh) * 2019-12-24 2020-04-07 东北大学 一种复合氧化物质子导体材料及其制备方法
US11198941B2 (en) * 2017-02-03 2021-12-14 Battelle Energy Alliance, Llc Methods for hydrogen gas production through water electrolysis
WO2022064196A1 (fr) * 2020-09-24 2022-03-31 Ceres Intellectual Property Company Limited Structure de pérovskite, méthode de production et application dans des électrodes et des piles à oxyde solide
KR20230095367A (ko) * 2021-12-22 2023-06-29 김연수 프로톤 세라믹 연료전지의 성능 향상을 위한 bzy 기능 층 삽입

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108091885A (zh) * 2016-11-21 2018-05-29 中国科学院大连化学物理研究所 一种高温燃料电池阴极及其应用
US11198941B2 (en) * 2017-02-03 2021-12-14 Battelle Energy Alliance, Llc Methods for hydrogen gas production through water electrolysis
CN110970148A (zh) * 2019-12-24 2020-04-07 东北大学 一种复合氧化物质子导体材料及其制备方法
WO2022064196A1 (fr) * 2020-09-24 2022-03-31 Ceres Intellectual Property Company Limited Structure de pérovskite, méthode de production et application dans des électrodes et des piles à oxyde solide
KR20230095367A (ko) * 2021-12-22 2023-06-29 김연수 프로톤 세라믹 연료전지의 성능 향상을 위한 bzy 기능 층 삽입

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