Synthesis of ceramic perovskites and fabrication of ceramic proton conducting button cell electrolyte (PCC's) for solid oxide fuel cells (SOFC).

摘要

Ceramic perovskites, particularly ziconia based perovskites doped with rare earth elements can be used as ceramic powders to fabricate proton conducting ceramic electrolyte button cells for fuel cells operating at intermediate temperatures. Ziconia based perovskites were the most stable to CO2 and H2O atmospheres, important in ability of the electrolyte to function in a fuel cell at high or low temperatures. Results from Xray and neutron diffraction studies comparing samples of perovskite powders synthesized by solid oxide synthesis and glycine nitrate (autoignition) were compared. Solid oxide synthesis appears to a practical synthesis route for the production of ceramic powders.;Fabrication methods by die pressing was effective, however, novel methods such as spin coating of slurry paste of sample of synthesized ceramic perovskite onto anode supports showed promise. Spin coating was explored as an alternative due to concerns with the thickness of the fabricated PCC button cell using die pressing. Conductivity measurements using impedance spectroscopy where the fuel cell's anode was exposed to pure hydrogen at atmospheric pressure, and the cathode was exposed to air at 50% relative humidity and atmospheric pressure at room temperature were conducted. tH+ was determined to be 0.865. This number indicates that the vast majorities (86.5%) of charge carriers at room temperature were protons, and the material shows promise for use in a protonic fuel cell. Also, power and current density curves showed open circuit voltages of 0.8V, and 1.02V respectively (no current, infinite resistance), while also recording a voltage with increasing current; however, the observed voltage drops off very quickly. This might be due to hydrogen leakage within the cell. In general, the electrolyte in the fuel cell can be said to be functional.