Fabrication and preliminary testing of patterned silver cathodes for proton conducting IT-SOFCs

Abstract

Dense silver (Ag) cathodes with defined triple phase boundary (TPB between the interface of electrolyte, electrode, and gas) lengths (L_TPB) and electrode areas (A_ELT) were fabricated by photolithography and E-beam evaporation over a proton conducting BaZr_0.4Ce_0.4Y_0.1Yb_0.1O_3−δ (BZCYYb4411) electrolyte. A bi-layer lift-off resist method appears to be more versatile than a single layer lift-off resist method for successful patterned cathode fabrication. The electrochemical behaviors of the patterned Ag cathodes over the BZCYYb4411 electrolyte were tested by electrochemical impedance spectroscopy (EIS) at different temperatures in atmospheres with different concentrations of O₂ and H₂O. The results were processed using Distribution of Relaxation Times (DRT) and reaction order analyses and also fitted to equivalent circuits. The directions for future work on patterned electrodes with different L_TPB and A_ELT and theoretical calculations to gain further insights into the kinetics and mechanism of the cathode oxygen reduction reaction (ORR) over proton conducting electrolytes are pointed out.