The performance of conventional La0.80Sr0.20MnO3-delta (LSM) cathodes was dramatically improved using a highly conductive Er-0.4Bi1.6O3 (ESB) phase. ESB was utilized not only as the ion-conducting phase in the LSM-ESB cathode, but also as an electrolyte coupled to the LSM-ESB cathode. The electrode area specific resistance (ASR) measured from a symmetric cell consisting of LSM-ESB electrodes on an ESB electrolyte was only 0.43 Omega cm(2) at 600 degrees C, which is similar to 60% lower than that of identical LSM-ESB cathodes on Gd0.1Ce0.9O1.95 (GDC) electrolytes (1.11 Omega cm(2)). Deconvolution of the impedance spectra reveals that this significantly smaller cathode ASR with an ESB electrolyte is due to a higher rate of oxygen incorporation at the cathode/ESB electrolyte interface. The maximum power density (MPD) of an anode-supported solid oxide fuel cell (SOFC) with an LSM-ESB cathode on an ESB/GDC bilayered electrolyte reached similar to 1013 mW cm(-2) at 650 degrees C. The measured MPDs at low temperatures, from 450 to 650 degrees C, are to date the highest reported values for SOFCs using LSM-based composite cathodes. (C) 2012 Elsevier B.V. All rights reserved.