Functional properties of SOFC anode materials based on LaCrO3, La(Ti,Mn)O-3 and Sr(Nb,Mn)O-3 perovskites: A comparative analysis

Abstract

The electrochemical, transport and thermomechanical properties of perovskite-type (La-1 (-) Sr-x(x))(1 - y)Mn0.5Ti0.5O3 (-) (delta) (x = 0.15-0.75; y = 0-0.05), (La0.75 - xSr0.25 + x)(0.95)Mn0.5Cr0.5 - xTixO3 - delta (x = 00.5), (La0.75Sr0.25)(0.95)Cr1 - xFexO3 (- delta) (x = 0.3-0.4), SrNb1 - xMnxO3 - delta (x = 0.50.8) and (La0.9Sr0.1)(0.95)Cr0.85Mg0.1Ni0.05O3 - delta have been appraised in light of their applicability for solid oxide fuel cell (SOFC) anodes. The electrical conductivity, measured in the oxygen partial pressure range of 10(-20) to 0.5 atm at 940-1270 K, increases with manganese and strontium additions which lead, however, to higher reducibility. In addition to the thermodynamic stability limitations under the SOFC anodic conditions, the latter factor raises the importance of chemically induced expansion, as for Fe-substituted (La,Sr)CrO3 (- delta). The reduction of Ni-doped chromite results in the formation of nanosized metallic particles dispersed on the perovskite surface, and has no significant effect on the transport properties governed by the perovskite phase. The maximum electrochemical performance was observed for porous La0.5Sr0.5Mn0.5Ti0.5O3 - delta, (La0.9Sr0.1)(0.95)Cr0.85Mg0.1Ni0.05O3 - delta and (La0.75Sr0.25)(0.95)Cr0.7Fe0.3O3 - delta electrodes in the electrochemical cells with lanthanum gallate-based solid electrolyte and Ce0.8Gd0.2O2 - delta interlayers. (C) 2013 Elsevier B.V. All rights reserved.