The electrochemical performance and microstructure of LSCF/CGO composite SOFC cathodes are studied on symmetrical cells. The best performing LSCF/CGO cathode shows polarization resistances as low as 136 mΩ cm~2 at 600°C, 60 mΩ cm~2 at 650°C and 20 mΩ cm~2 at 750°C. The changes in the electrical impedance spectra (EIS) as a function of time and p(O2) has been studied and it is shown that for cells with a high degradation rate, it is mainly the lower frequency range of the impedance spectra that is affected, pointing to a degradation of the oxygen exchange rate on the surface of LSCF as the process responsible for the degradation.^
展开▼
