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 co-doped ceria Ce0.8Gd0.05Y0.15O1.9 (GYDC) and a binary carbonate-based (52 mol% Li2CO3/48 mol% Na2CO3), 1.2 mm thick electrolyte layer has been developed. Co-doped Ce0.8Gd0.05Y0.15O1.9 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 °C when the carbonates melted. Single cells with thick electrolyte layer were fabricated by a dry-pressing technique using NiO as anode and Ba0.5Sr0.5Co0.8Fe0.2O3−δ or lithiated NiO as cathode. The cell was tested at 450–550 °C using hydrogen as the fuel and air as the oxidant. Excellent performance with high power density of 670 mW cm−2 at 550 °C was achieved for a 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 μm thick electrolyte layer.