title: Impact of Oxygen Deficiency on the Electrochemical Performance of K2NiF4-Type (La1-xSrx)2NiO4-δOxygen Electrodes.
abstract: Perovskite-related (La1-xSrx)2NiO4-δ(x=0.5-0.8) phases were explored for possible use as oxygen electrodes in solid electrolyte cells with a main focus on the effect of oxygen deficiency on the electrocatalytic activity. (La1-xSrx)2NiO4-δsolid solutions were demonstrated to preserve the K2NiF4-type tetragonal structure under oxidizing conditions. Acceptor-type substitution by Sr is compensated by the formation of oxygen vacancies and electron holes and progressively increases high-temperature oxygen nonstoichiometry, which reaches as high as δ=0.40 for x=0.8 at 950 °C in air. The electrical conductivity of (La1-xSrx)2NiO4-δceramics at 500-1000 °C and p(O2)≥10-3atm is p-type metallic-like. The highest conductivity, 300 S cm-1at 800 °C in air, is observed for x=0.6. The average thermal expansion coefficients, (14.0-15.4)×10-6K-1at 25-900 °C in air, are sufficiently low to ensure the thermomechanical compatibility with common solid electrolytes. The polarization resistance of porous (La1-xSrx)2NiO4-δelectrodes applied on a Ce0.9Gd0.1O2-δsolid electrolyte decreases with increasing Sr concentration in correlation with the concentration of oxygen vacancies in the nickelate lattice and the anticipated level of mixed ionic-electronic conduction. However, this is accompanied by increasing reactivity between the cell components and necessitates the microstructural optimization of the electrode materials to reduce the electrode fabrication temperature.
authors.affiliation: CICECO-Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193, Aveiro, Portugal.|Department of Chemistry, Belarusian State University, Leningradskaya 14, 220006, Minsk, Belarus.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Kravchenko
authors.affiliation: CICECO-Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193, Aveiro, Portugal.
authors.forename: Kiryl
authors.initials: K
authors.lastname: Zakharchuk
authors.affiliation: Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya 14, 220006, Minsk, Belarus.
authors.forename: Alexander
authors.initials: A
authors.lastname: Viskup
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden.
authors.forename: Jekabs
authors.initials: J
authors.lastname: Grins
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Svensson
authors.affiliation: Department of Chemistry, Belarusian State University, Leningradskaya 14, 220006, Minsk, Belarus.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pankov
authors.affiliation: CICECO-Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193, Aveiro, Portugal.
authors.forename: Aleksey
authors.identifier: 0000-0002-3837-5946
authors.initials: A
authors.lastname: Yaremchenko
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D004553:Electric Conductivity; D004563:Electrochemistry; D004566:Electrodes; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D014025:Titanium; D010100:Oxygen
keywords: ceramics; electrochemistry; fuel cells; layered compounds; nonstoichiometric compounds