Infiltrated Lanthanum Nickelate Cathodes for Use with BaCe0.2Zr0.7Y0.1O3-δ Proton Conducting Electrolytes.

Symmetric cells (electrode/electrolyte/electrode) were prepared using BaCe_0.2Zr_0.7Y_0.1O_3-δ (BCZY27) as a proton conducting electrolyte. Porous BCZY27 backbones were sintered on each side of the electrolyte. Lanthanum nickelate, La₂NiO_4+δ (LN), was infiltrated into the porous BCZY27 backbone to act as the electrode. Pure phase LN was formed after annealing in air at 850°C for 4 h. Electron microscopy was used to observe LN nano-particles (~50 nm) infiltrated throughout the backbone. Impedance spectra were recorded at 500, 600, and 700°C with four oxygen partial pressures and four steam partial pressures. Four arcs were observed in the spectra corresponding to: BCZY27 backbone grain-boundary resistance, charge-transfer, oxygen dissociation/adsorption, and gas transport. Total area specific resistances (ASRs) were found to decrease with increasing oxygen partial pressure. Total cathode ASRs of 161.8, 29.3, and 3.7 Ω⋅cm² were measured in 3% humidified air at 500, 600, and 700°C respectively. [ABSTRACT FROM AUTHOR]