La[sub 0.4]Sr[sub 0.6]Ti[sub 1−x]Mn[sub x]O[sub 3−δ] Perovskites as Anode Materials for Solid Oxide Fuel Cells

Abstract

Perovskite oxides, La0.4 Sr0.6 Ti1-x Mnx O3-δ (x=0, 0.2, 0.4, 0.6), have been investigated in the search for new solid oxide fuel cell (SOFC) anode materials. La0.4 Sr0.6 Ti0.4 Mn0.6 O3-δ (LSTM4646) shows an electrical conductivity of 22.6 Scm in air and 1.5 Scm in wet Ar/4% H2 [p (O2) ≈ 10-18 bar] at 810°C. It is thermally and chemically compatible with yttria-stabilized zirconia (YSZ) electrolytes. Three processes govern the electrochemical performance of LSTM4646/YSZ anodes in wet Ar H2 or wet C H4. They are proposed to be charge transfer at the LSTM4646/YSZ interface, dissociative adsorption of hydrogen on the electrode surface, and gas conversion impedance, respectively. Due to the low polarization resistance of the LSTM4646/YSZ anode, 0.32 Ω; cm2, an electrolyte-supported H2 /air fuel cell with an LSM/YSZ cathode yields a power density of 365 mW cm-2 at 0.7 V at 856°C. In addition, this anode material is stable under a moderately humidified hydrogen atmosphere. It shows insignificant catalytic activity for the direct oxidation of methane however. © 2006 The Electrochemical Society. All rights reserved.