Cathode-supported SOFC using a highly conductive lanthanum aluminate-based electrolyte

Abstract

A newly-developed, highly conductive, and cost-effective LaAlO 3-based perovskite was used as a solid electrolyte to replace costly LaGaO 3 in this study. The La 0.9Ba 0.1Al 0.9Y 0.1O 3 (LBAYO) solid electrolyte was fabricated by codoping 10 at.% Ba and 10 at.% Y into the cation sublattice of LaAlO 3. The conductivity of the doubly doped La 0.9Ba 0.1Al 0.9Y 0.1 O 3 was enhanced to 184 × 10 − 4 S cm − 1 which is about 50 times higher than that of the undoped one at 800 °C. Cathode-supported cells consisting of Ni/yttria-stabilized zirconia (Ni/YSZ) anode, a thin LBAYO electrolyte (~ 63 μm), a samarium doped ceria (SDC) interlayer, and a lanthanum strontium manganite (LSM) cathode were assembled and tested. The LBAYO electrolyte film was first prepared on conductive LSM substrates using the electrophoretic deposition (EPD) technique. The cathode-supported structure, consisting of an LBAYO film on a porous LSM substrate, was co-fired at 1450 °C for 2 h. A crack-free LBAYO film with a uniform thickness supported on a porous LSM substrate was obtained. Subsequently, a 10 μm-thick SDC buffer interlayer between the electrolyte and 30 μm-thick NiO/YSZ anode was screen-printed and fired on the electrolyte film. A 10-day test showed essentially no degradation on the output power from the cell using the LBAYO electrolyte. These tests convincingly demonstrated the feasibility of an SOFC using LBAYO as the electrolyte when operated at temperatures ranging from 600 °C to 800 °C.