Mixed ionic-electronic conductivity, phase stability and electrochemical activity of Gd-substituted La2NiO4+delta as oxygen electrode material for solid oxide fuel/electrolysis cells

authors	Pikalova, E; Kolchugin, A; Zakharchuk, K; Boiba, D; Tsvinkinberg, V; Filonova, E; Khrustov, A; Yaremchenko, A
nationality	International
journal	INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
author keywords	Lanthanum nickelate; Oxygen nonstoichiometry; Ionic conductivity; Oxygen electrode; Polarization resistance; Solid oxide fuel cell
keywords	TRANSPORT-PROPERTIES; NICKEL(III) OXIDE; CATHODE MATERIALS; FUEL-CELLS; LN(2)NIO(4+DELTA) LN; MAGNETIC-PROPERTIES; CRYSTAL-STRUCTURE; COMPLEX OXIDES; LA; PEROVSKITE
abstract	Ruddlesden-Popper La2-xGdxNiO4+delta (x = 0-0.4) nickelates were synthesized by glycerolnitrate combustion technique and explored as potential oxygen electrode materials for solid oxide fuel/electrolysis cells. Similar to the parent La2NiO4+delta, the metastability of RP-type n = 1 structure limits the applicability of La2-xGdxNiO4+delta to temperatures below 900 degrees C. These solid solutions are mixed conductors with predominantly p-type electronic conductivity that exceeds 50 S/cm at 500-800 degrees C in air. Substitution by gadolinium does not change the overstoichiometric oxygen content in air but has a negative impact on the mobility of interstitial oxygen, most likely, due to steric effects associated with the lattice shrinkage on doping. The electrochemical activity of bilayer electrodes comprising functional La2-xGdxNiO4+delta and current collecting LaNi0.6Fe0.4O3-delta + 3 wt% CuO layers in contact with Ce0.8Gd0.2O1.9 electrolyte was studied in air at 550-850 degrees C. Analysis of electrochemical impedance spectroscopy data employing the ALS (Adler-Lane-Steele) model revealed the limiting role of oxygen-ionic conductivity of functional La2-xGdxNiO4+delta materials in overall electrode performance. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
publisher	PERGAMON-ELSEVIER SCIENCE LTD
issn	0360-3199
isbn	1879-3487
year published	2021
volume	46
issue	32
beginning page	16932
ending page	16946
digital object identifier (doi)	10.1016/j.ijhydene.2021.03.007
web of science category	15
subject category	Chemistry, Physical; Electrochemistry; Energy & Fuels
unique article identifier	WOS:000644993100012