LSM-YSZ CATHODES FOR MEDIUM-TEMPERATURE SOLID OXIDE FUEL CELLS

摘要

The effect of cathode composition, processing, and structure on the performance of medium-temperature (600-800℃) solid oxide fuel cells (SOFCs) is described. The SOFC cathodes were two-phase mixtures of (La_(1-x)Sr_x)_(1-y)MnO_3 (LSM) and Yttria-stabilized Zirconia (YSZ). The electrolytes were < 10μm thick YSZ, and the anodes were Ni-YSZ with Y-doped CeO_2 interfacial layers. The cathode overpotential was the primary factor limiting cell power densities. Increasing the YSZ volume fraction in LSM-YSZ cathodes from 0 to 60% reduced the low-current area-specific resistance of the cells (in air and humidified hydrogen) from ～3.3 to 0.7 Ω cm~2 at 750℃. The use of LSM with y=0.1 suppressed the formation of zirconate phases during cathode sintering. Optimal cathode porosity was ≈ 40%. The maximum power densities measured in humidified H_2 and air ranged from ～110 mW/cm~2 at 600 to 470 mW/cm~2 at 800℃.