A NiO/Yttrium-stabilized zirconia (YSZ) transition layer and/or a SDC function layer were introduced into the anode/electrolyte and/or electrolyte/cathode interface to decrease the activation polarization resulted from the mass transfer at electrode/electrolyte interface. With a NiO/YSZ transition layer, the activation polarization simulated from I-V curves drops from 4.42 to 2.42 Omega cm(2) at 600 degrees C, about 45% less than that of cell I; with additional SDC function layer, no activation polarization is obviously observed. The cell performance was also remarkably improved with the introduction of both the transition layer and the SDC function layer. Peak power densities of 187 and 443 mW cm(-2) at 600 and 650 degrees C, respectively, were achieved for a single cell with both a transition layer and a function layer, with an increment of 87% and 95% compared to that of the cell without any structural improvement, and about 30% and 25% compared to that of the cell with only anode transition layer. The study by ac impedance spectroscopy technique also indicated that the interfacial polarization resistance, the main source of cell resistance, could be effectively reduced by interface improvement. (C) 2008 Elsevier B.V. All rights reserved.