Evaluation of BaZr0.1Ce0.7Y0.2O3−δ-based proton-conducting solid oxide fuel cells fabricated by a one-step co-firing process

Proton-conducting solid oxide fuel cells, incorporating BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY) electrolyte, NiO–BZCY anode, and Sm_0.5Sr_0.5CoO_3−δ–Ce_0.8Sm_0.2O_2−δ (SSC–SDC) cathode, were successfully fabricated by a combined co-pressing and printing technique after a one-step co-firing process at 1100, 1150, or 1200 °C. Scanning electron microscope (SEM) results revealed that the co-firing temperature significantly affected not only the density of the electrolyte membrane but the grain size and porosity of the electrodes. Influences of the co-firing temperature on the electrochemical performances of the single cells were also studied in detail. Using wet hydrogen (2% H₂O) as the fuel and static air as the oxidant, the cell co-fired at 1150 °C showed the highest maximum power density (PD_max) of 552 and 370 mW cm⁻² at 700 and 650 °C, respectively, while the one co-fired at 1100 °C showed the highest PD_max of 276 and 170 mWcm⁻² at 600 and 550 °C, respectively. The Arrhenius equation was proposed to analyze the dependence of the PD_max on the operating temperature, and revealed that PD_max of the cell co-fired at a lower temperature was less dependent on operating temperature. The influences of the co-firing temperature on the resistances of the single cells, which were estimated from the electrochemical impedance spectroscopy measured under open circuit conditions, were also investigated.