Enhanced Chromium Tolerance of Gd_(0.1)Ce_(0.9)O_(1.95) Impregnated La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) Electrode of Solid Oxide Fuel Cells

摘要

The electrochemical activities and chromium tolerances are studied on pure La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (LSCF) and Gd_(0.1)Ce_(0.9)O_(1.95)(GDC) impregnated LSCF (GDC-LSCF) electrodes of solid oxide fuel cells. Using electrochemical impedance spectroscopy (EIS) technology, a significant reduction in the electrode polarization resistance (Re) for O_2 reduction particularly at low temperatures is obtained after GDC impregnated. Form the analysis results of EIS, the low frequency resistances are markedly reduced due to a positive effect of GDC coating on oxygen dissociative adsorption process. Most importantly, the overpotential (η) of GDC-LSCF electrode at 800 °C for 40 h in the presence of Fe-Cr metallic interconnect presents more stable than that of pure LSCF electrode, implying an enhanced Cr tolerance after GDC introduced. Moreover, SEM-EDS results indicate that Cr deposition is selective and occurs preferentially on LSCF surface rather than GDC, suggesting that GDC impregnation is a promising technique for the development of Cr-tolerance electrode in SOFCs.