Performance of a fuel cell using Sn 0.9 In 0.1 P 2 O 7 as the electrolyte was evaluated in the temperature range of 150-300°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°C, estimated from the IR drop, were comparable to the ac conductivity values ͑1.48 ϫ 10 −1 -1.95 ϫ 10 −1 S cm −1 ͒ of the electrolyte. The cell performance was improved by forming an intermediate layer consisting of Sn 0.9 In 0.1 P 2 O 7 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°C using the 0.35-mm-thick electrolyte. The present fuel cell also showed high stability at low relative humidities ͑p H 2 O Ϸ 0.0075 atm͒ and 10% CO concentration.

No abstract