from first principles PP-I-1

PP-V-2Oxygen Exchange and Degradation of LSM―YSZ Cathode MaterialsAnanyev M.V., Porotnikova N.M., Medvedev D.A., Eremin V.A., Yaroslavtsev I.Yu.,Pankratov A.A., Kurumchin E.Kh.Institute of High Temperature Electrochemistry UB RAS, Yekaterinburg, Russiawedney@yandex.ruComposite (1–x)·LSM―x·YSZ based materials are successfully used as cathode materials inSolid Oxide Fuel Cells. The interphase exchange rate and the apparent oxygen diffusioncoefficient were measured by the isotope exchange method with gas phase analysis for x = 0―1;T = 600―850°C; Po 2 = 10 –3 ―10 –1.5 atm and for x = 0.6 at T = 800°C,Po 2 = 10 –2 atm during 1000 hours. The electrical resistivity of the samples was measured by a dc4-probe method at the same temperature and oxygen partial pressure during 1000 hours. Themicrostructure of the samples was studied by SEM on a JSM 5900LV with INCA Energyspectrometer after 0, 40, 500 and 1000 hours of the exposure time. Electrical conductivity wasfound to increase in time during exposure at 800°C and Po 2 = 10 –2 atm, whereas both the oxygeninterphase exchange rate and the diffusion coefficient decrease at the same conditions, seeFigure 1 Microstructure analysis allows to determine the microstructure changes with thecomposite phase ratio and the specific triple-phase boundary length dependence on time to predictthe polarization resistivity behaviour measured by EIS method. The mechanism of the oxygenexchange and degradation of LSM―YSZ is discussed.Fig. 1. Conductivity (σ), interphase exchange rate (H) and oxygen diffusion coefficient (D)time dependences for LSM―YSZ at 800°C, Po 2 = 10 –2 atm.This work was partly supported by the grant for the young scientists of Ural Branch ofRussian Academy of Sciences in 2012.311