Electrochemical Performance of Solid Oxide Cell Oxygen Electrodes Under Pressurization

The solid oxide cell (SOC) composite oxygen electrodes (La 0.8 Sr 0.2 ) 0.98 MnO 3-δ - Zr 0.84 Y 0.16 O 2-γ (LSM-YSZ) and La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3-d (LSCF) - Ce 0.8 Gd 0.2 O 1.95 (LSCF-GDC) were studied at oxygen partial pressure pO 2 from 0.1 to 10 atm by impedance spectroscopy. Two primary responses were observed in the impedance spectra, which were fit using an equivalent circuit model with two RQ elements. A higher frequency response observed at ~ 10 3 Hz varied as pO 2 -0.25 . A lower frequency response observed at ~ 10 to 100 Hz varied as pO 2 -0.15 . Total electrode resistances decreased with increasing pO 2 following a pO 2 -0.17 dependence for LSM-YSZ and a pO 2 -0.20 dependence for LSCF-GDC. Overall, the area-specific resistance of these SOC oxygen electrodes is reduced by a factor of ~2 by increasing oxygen pressure from a nominal 0.2 atm (air) to 10 atm, thereby improving pressurized SOC performance.