Layered perovskite LaBaCuMO_5+x (M = Fe, Co) cathodes for intermediate-temperature protonic ceramic membrane fuel cells

Layered perovskite LaBaCuFeO_5+x (LBCF) and LaBaCuCoO_5+x (LBCC) oxides are synthesized by a modified Pechini method and examined as potential cathode materials for intermediate-temperature protonic ceramic membrane fuel cells (IT-PCMFCs). Thin proton-conducting BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) electrolyte and NiO-BaZr_0.1Ce_0.7Y_0.2O_3-δ (NiO-BZCY) anode functional layer are prepared over porous anode substrates composed of NiO-BaZr_0.1Ce_0.7Y_0.2O_3-δ by a one-step dry-pressing/co-firing process. Laboratory-sized quad-layer cells of NiO-BYCZ/NiO-BYCZ/BYCZ/LBCF (LBCC) are operated from 550 to 700 °C with humidified hydrogen (∼3% H₂O) as fuel and the static air as oxidant. The single cell with LBCF cathode shows peak power densities of only 327 mW cm^-2 at 700 °C and 105 mW cm^-2 for 550 °C, while the single cell with LBCC cathode shows peak power densities of 432 and 171 mW cm^-2 at 700 and 550 °C, respectively. The dramatic improvement of cell performance is attributed to higher cobaltites catalytic activity than that of ferrites for IT-PCMFCs, which is in good agreement with the results of impedance measurement.