Electrochemical characterization of the n = 2 Ruddlesden-Popper phases Sr2(FeM)O6+ (M : Fe, Co, Ni) by electrochemical impedance spectroscopy

L. MOGNI; A. CANEIRO; F. PRADO

Chicago

Encuentro; 211th ECS Meeting; 2007

the Electrochemical Society

The electrochemical characterization of the porous Sr3FeMO6+δ (M = Fe, Co, Ni) electrode materials has been performed by a.c. electrochemical impedance spectroscopy (EIS) under pure O2 atmosphere and temperatures between 500 and 800 ºC. Thick films of porous Sr3FeMO6+δ were deposited on both sides of a dense Ce0.9Gd0.1O2-x electrolyte disc by spray deposition. To reach an adequate adherence between electrolyte and electrodes the cell was heat treated at 1000 ºC during 1 h. XRD and SEM were used to evaluate the structure and microstructure of the cells before and after the EIS measurements. Data of the Area Specific Resistance (ASR), defined by ASR = Z´(ω→0)-Z´(ωHF), associated with the overall oxygen reduction reaction, were obtained for the three compositions (Sr3Fe2O6+δ, Sr3FeCoO6+δ, Sr3FeNiO6+δ ). The ASR values are quite similar for the Sr3FeNiO6+δ and Sr3FeCoO6+δ compositions, and they are higher than those of Sr3Fe2O6+δ. The activation energy (Ea) corresponding to the ASR for the Sr3FeNiO6+δ material (∼1.3 eV) is higher than those of Sr3FeCoO6+δ and Sr3Fe2O6+δ, (∼ 0.9-1.0 eV).