International Journal of Hydrogen Energy, Vol.42, No.49, 29443-29453, 2017
(La,Sr)(Fe,Co)O-3-based cathode contact materials for intermediate-temperature solid oxide fuel cells
Development of the cathode contact materials (CCMs) for intermediate-temperature solid oxide fuel cells (IT-SOFCs) is a relatively new task promoted by the appearance of full-sized cells, which may operate below 700 degrees C with sufficient performance, on the market. CCM must ensure a low-resistive interface between interconnect and cathode and is supposed to be sintered at temperatures below 800 degrees C, as imposed by the specifications of IT-SOFCs and corresponding sealants. The present work is focused on the elaboration of CCMs derived from perovskite-like La0.6Sr0.4Co0.2Fe0.8O3-delta employing two approaches: introduction of the A-site cation vacancies and partial substitution by copper in B sublattice. Both approaches were found to result in a higher electrical conductivity below 800 degrees C if compared to the parent material. All studied materials exhibit acceptable coefficients of thermal expansion, 13.5-14.8 ppm K-1 at 25-700 degrees C. Area-specific resistance (ASR) of CCM/chromium barrier (Mn1.5Co1.5O4)/interconnect (Crofer 22APU) assemblies prepared by the screen-printing was measured in air at 660-750 degrees C. The studies revealed that morphology of CCM powder should be considered as a key parameter in the formation of interfaces with a low resistivity. The best ASR values, below 4 m Omega cm(2) at 660-700 degrees C, were obtained for La0.6Sr0.4Co0.15Cu0.10Fe0.75O3-delta, La0.6Sr0.4Co0.15Cu0.05Fe0.80O3-delta and (La0.60Sr0.40)(0.995)Co-0.20 Fe0.80O3-delta as CCMs. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Keywords:SOFC;Interconnect;Area-specific resistance;Cathode contact material;Crofer 22 APU;Chromium barrier