Functionally graded cathodes for solid oxide fuel cells

Functionally graded Solid Oxide Fuel Cell cathodes have been prepared from mixtures of strontium doped lanthanum manganite (LSM) and yttria stabilised zirconia (YSZ) using screen printing techniques. Samples were characterise d using scanning electron microscopy, elemental dot mapping, and electroche mical impedance spectroscopy. Characterisation using AC impedance technique s showed that each cathode could be analysed in terms of a low frequency, m id frequency and high frequency response. Results showed that as the level of YSZ-LSM grading within the cathode increased, the polarisation resistanc e decreased. No region of the graded cathode should contain less than 20 wt % LSM to prevent an accompanying increase in series resistance. (C) 2001 Kl uwer Academic Publishers.