LaCrO_3-based anodes: stability considerations

摘要

LaCrO_3 based materials have been studied as alternative anodes to the conventional Ni-YSZ cermet. Thermodynamic calculations as well as experimental work have been conducted in an attempt to analyze the stability of this system when doped with Mg, Ca, Sr, Mn, Fe, Co and Ni. Various gas atmospheres were simulated (air, humidified hydrogen, CO and CO_2). It was possible to correlate some of the experimental results (electrochemical, XRD, XPS-Auger, SIMS and TEM-EDS) with the thermodynamic calculations. It was calculated that Sr and Mn substitution maintain the stability of the perovskite even in the severe reducing conditions used in SOFC, whereas the other substitutions destabilize the system. Experimentally, transition metal substituted LaCrO_3 did not decompose readily in the reducing atmospheres containing wet hydrogen or methane indicating that the demixing is at least kinetically hindered.