A high performance intermediate temperature fuel cell based on a thick oxide-carbonate electrolyte

A high performance intermediate temperature fuel cell (ITFC) with composite electrolyte composed of codoped ceria Ce(0.8)Gd(0.05)Y(0.15)O(1.9) (GYDC) and a binary carbonate-based (52 mol Li(2)CO(3)/48 mol Na(2)CO(3)), 1.2 mm thick electrolyte layer has been developed. Co-doped Ce(0.8)Gd(0.05)Y(0.15)O(1.9) was synthesized by a glycine-nitrate process and used as solid support matrix for the composite electrolyte. The conductivity of both composite electrolyte and GYDC supporting substrate were measured by AC impedance spectroscopy. It showed a sharp conductivity jump at about 500 degrees C when the carbonates melted. Single cells with thick electrolyte layer were fabricated by a dry-pressing technique using NiO as anode and Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-delta) or lithiated NiO as cathode. The cell was tested at 450-550 degrees C using hydrogen as the fuel and air as the oxidant. Excellent performance with high power density of 670 mW cm(-2) at 550 degrees C was achieved fora 1.2 mm thick composite electrolyte containing 40 wt carbonates which is much higher than that of a cell based on pure GYDC with a 70 mu m thick electrolyte layer.