Development of LSM/YSZ composite cathode for anode-supported solid oxide fuel cells

This paper presents the effect of (La, Sr)MnO₃ (LSM) stoichiometry on the polarization behaviour of LSM/Y₂O₃-ZrO₂ (YSZ) composite cathodes. The composite cathode made of A-site deficient (La_0.85Sr_0.15)_0.9MnO₃ (LSM-B) showed much lower electrode interfacial resistance and overpotential losses than that made of stoichiometric (La_0.85Sr_0.15)_1.0MnO₃ (LSM-A). The much poorer performance of the latter is believed to be due to the formation of resistive substances such as La₂Zr₂O₇/SrZrO₃ between LSM and YSZ phases in the composite electrode. A slight A-site deficiency (∼0.1) was effective in inhibiting the formation of these resistive substances. A power density of ∼1 W cm^-2 at 800°C was achieved with an anode-supported cell using an LSM-B/YSZ composite cathode. In addition, the effects of cathodic current treatment and electrolyte surface grinding on the performance of composite cathodes were also studied.