Performance of an intermediate-temperature fuel cell using a proton-conducting Sn0.9In0.1P2O7 electrolyte

Performance of a fuel cell using Sn0.9In0.1P2O7 as the electrolyte was evaluated in the temperature range of 150-300 degrees C under unhumidified conditions. The IR drop and electrode overpotential of the cell were measured separately by the current interruption method. The dc conductivity values of the electrolyte between 150 and 300 degrees C, estimated from the IR drop, were comparable to the ac conductivity values (1.48 X 10(-1)-1.95 X 10(-1) S cm(-1)) of the electrolyte. The cell performance was improved by forming an intermediate layer consisting of Sn0.9In0.1P2O7 and Pt/C catalyst powders at the interface between the electrolyte and cathode, which significantly reduced the cathode polarization. As a result, the peak power density reached 264 mW cm(-2) at 250 degrees C using the 0.35-mm-thick electrolyte. The present fuel cell also showed high stability at low relative humidities (p(H2O) approximate to 0.0075 atm) and 10% CO concentration. (c) 2006 The Electrochemical Society.