Applicability of BSCF as IT-SOFC Cathode in CO2-Containing Atmospheres

摘要

In the present study, the new intermediate temperature SOFC cathode material Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF5582) is investigated by precision thermogravimetry in controlled O2-CO2-Ar atmospheres at 20600°C. Decomposition of the carbonate in CO2-rich atmosphere occurs at T～800°C. Time-dependent experiments at constant temperature and oxygen partial pressure (T=600°C, pO2=0.2 bar), but variable pCO2 show a continuous mass gain due to CO2 for 24.h, without reaching an equilibrium state. Dynamic heating/cooling experiments on a CO2-containing sample indicate that regeneration in CO2-free atmospheres occurs at T≥600°C, with a maximum desorption rate around 800°C. The oxygen uptake characteristics of the regenerated sample are comparable to the fresh reference sample. Alternatively, two promising alternatives for IT-SOFC cathodes, La_(0.6)Sr_(0.4)CoO_(3-δ) and La_(0.5)8Sr0.4Co_(0.2)Fe_(0.8)O_(3-δ) are investigated in CO2-containing atmospheres. Both materials exhibit excellent stability, even vs. high CO2 contents, in the whole T range under investigation (20-900°C).^