Improvement of LSM Cathode for High Power Density SOFCs

Abstract

Optimisation of processing (La 1-x Sr x ) y MnO 3±δ composite cathodes has led to high-performance solid oxide fuel cells (SOFCs). Symmetric cells were prepared with (La 1-x Sr x ) y MnO 3±δ composite cathode on yttria-stabilised zirconia tapes. A homogeneous microstructure with submicron pores was obtained that has resulted in a low area-specific polarisation resistance of 0.09 Ωcm 2 at 850°C and 0.31 Ωcm 2 at 750°C, while area-specific series resistances are 0.29 Ωcm 2 and 0.61 Ωcm 2 , respectively, in a symmetric cell with a yttria-stabilised zirconia tape 185 μm thick. The low area-specific polarisation and series resistances are attributed to a long triple-phase boundary and very good adhesion between cathode and electrolyte. By impedance measurements the activation energy of the cathode was determined to be 1.26 eV. Anode-supported cells with an active area of 4x4 cm 2 show high power density of 1.44 W/cm 2 at 850°C and 0.8 W/cm 2 at 750°C at a cell voltage of 0.7 V.