Fluoride-Based, Low Temperature Solid Electrolyte Fuel Cell

Lanthanum fluoride electrolytes were tested to determine whether fluoride electrolytes can be used as fuel cell electrolytes at low temperatures. The planar-type fuel cell were operated in oxygen/hydrogen gases with nickel oxide/nickel as the anode and a perovskite-structure oxide (La_0.6Sr_0.4CoO₃) as the cathode. In order to reduce the fuel cell operating temperature while maintaining the highest possible current, various thin and thick film techniques were assessed. They include e-beam evaporation and DC plasma spray methods. Fuel cells incorporating plasma-sprayed LaF₃ films yielded a short-circuit current density on the order of 0.4 mA/cm² at 450°C, and the current density under an overpotential of 0.2V showed no sign of decay over 17 hours. In the co-ionic (fluoride and oxide ion) conduction mode, the lanthanum fluoride electrolyte based fuel cells could sustain current in oxygen/hydrogen gases.