Two-step co-sintering method to fabricate anode-supported Ba_3Ca_(1.18)Nb_(1.82)O_(9-δ) proton-conducting solid oxide fuel cells

摘要

Anode-supported solid oxide fuel cells (SOFCs) based on complex-perovskite structured Ba_3Ca_(1.18)Nb_(1.80)O_(9-δ) (BCN18) proton-conducting electrolyte membranes have been successfully fabricated by a novel two-step co-sintering method. BCN18 has been reported to have excellent chemical stability against H_2O and CO_2, but is relatively difficult to densify. In this study, dense BCN18 electrolyte membranes with fine grain size have been obtained by a novel two-step co-sintering method at a relatively low sintering temperature of 1,300 ℃, compared to the typical high sintering temperature of 1,550 ℃. Furthermore, the Ni-BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ) anode obtained by the novel two-step co-sintering method was composed of small particles with high porosity which is advantageous for electrode performance. Single fuel cells using BCN18 as the electrolyte, Ni-BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ) as anode and Ba_(0.9)Co_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) as cathode demonstrated a power density of 106 mW cm~(-2) at 750 ℃, the best fuel cell performance ever reported for the BCN18 electrolyte. These results suggest that the two-step co-sintering method is a promising method to optimize the microstructure, and combined with proper electrodes, enhanced performance of anode-supported SOFCs using BCN18 proton-conducting electrolyte can be obtained.