abstract
In the present work, the anionic doping of a Ba-containing Nd2NiO4+delta mixed conductor is proposed as an efficient means of tuning its functional properties for application as an oxygen/steam electrode material in protonic ceramic electrolysis cells (PCECs). Single-phase Nd1.9Ba0.1NiO4+delta F gamma(gamma = 0, 0.03, 0.05, 0.07 and 0.1) nickelates having a K2NiF4-type structure were prepared and comprehensively characterised in the range from room temperature to 1000 degrees C. A combination of complimentary techniques, including 4-probe DC electrical measurements, an electron-blocking method, electrochemical impedance spectroscopy and analysis of equivalent circuit schemes and distribution of relaxation times, was employed to reveal the fundamental correlations between electrical properties, oxygen-ionic transport and electrochemical performance of fluorinated nickelates. The highest ionic conductivity in combination with the lowest electrode polarisation resistance was found for the composition with gamma = 0.05. The enhanced transport properties of this material were attributed to mixed anion lattice effect. Electrochemical tests of an electrolysis cell based on a proton-conducting BaCe0.5Zr0.3Y0.1Y0.1O3-delta electrolyte with a Nd1.9Ba0.1NiO4+delta F0.05 oxygen electrode demonstrated competitive performance compared to state-of-the-art PCECs, thus supporting the prospective viability of the proposed approach. (C) 2020 Elsevier Ltd. All rights reserved.
keywords
OXIDE FUEL-CELLS; STRUCTURAL PHASE-TRANSITION; TRANSPORT-PROPERTIES; ELECTRICAL-PROPERTIES; HYDROGEN-PRODUCTION; CHEMICAL-STABILITY; RELAXATION-TIMES; CATHODE MATERIAL; CLEAN ENERGY; PERFORMANCE
subject category
Electrochemistry
authors
Tarutin, AP; Vdovin, GK; Medvedev, DA; Yaremchenko, AA
our authors
Aleksey Yaremchenko
Principal Researcheracknowledgements
This work was supported by the Russian Science Foundation [grant no. 16-19-00104]. Dr. D. Medvedev is grateful to the Council of the President of the Russian Federation [scholarship no-161.2018.1] for supporting the studies devoted to new MIEC materials, while Mr. A. Tarutin is grateful to the same foundation [scholarship no-1413.2019.1] for supporting the studies aimed at new strategies of Nd2NiO4thornd modification. A.A. Yaremchenko would like to acknowledge financial support by the FCT, Portugal (project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement).