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 BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte, NiO–BZCY anode, and Sm0.5Sr0.5CoO3−δ–Ce0.8Sm0.2O2−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 (PDmax) of 552 and 370 mW cm−2 at 700 and 650 °C, respectively, while the one co-fired at 1100 °C showed the highest PDmax of 276 and 170 mWcm−2 at 600 and 550 °C, respectively. The Arrhenius equation was proposed to analyze the dependence of the PDmax on the operating temperature, and revealed that PDmax 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.