Ru-doped lanthanum strontium titanates for the anode of solid oxide fuel cells

Abstract

Lanthanum strontium titanate perovsldte (LST) was doped with Ru (La0.4Sr0.6Ti1-xRuxO3-delta (LSTR), x = 0.02, 0.05), and its properties were characterized by various methods for possible use as the anode material in solid oxide fuel cells (SOFCs). The thermal expansion coefficients of Ru-doped samples (10.2-10.3 x 10(-6) K-1) are about the same as LST (10.4 x 10(-6) K-1), which is similar to that of YSZ. It has been found that under a reducing atmosphere, doped Ru is precipitated from the structure. This decreases the total electrical conductivity and increases the ionic conductivity because of the increased number of B-site deficiencies created by the Ru precipitation. Impedance spectra measured with the buttons cells of the LSTRs-YSZ/YSZ/LSM-YSZ/LSM configuration reveal that the polarization resistance with the LST-YSZ anode increases with time (from 4.95 Omega cm(2) to 5.78 Omega cm(2) in 24 h of H-2 fuel atmosphere), whereas the resistance with Ru-doped LST-YSZ anodes decreases with time (from 4.87 Omega cm(2) and 4.17 Omega cm(2) to 4.06 Omega cm(2) and 2.74 Omega cm(2) for the LSTR0.02-YSZ and LSTR0.05-YSZ anodes, respectively). Accordingly, the final maximum power density at 850 degrees C also increases from 52 mW/cm(2) for LST-YSZ to 74 mW/cm(2) and 115 mW/cm(2) for the LSTR0.02-YSZ and LSTR0.05-YSZ anodes, respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.