Y and Ni Co-doped BaZrO₃ as a proton-conducting solid oxide fuel cell electrolyte exhibiting superior power performance

The fabrication of anode supported single cells based on BaZr_0.8Y_0.2O_3-δ (BZY20) electrolyte is challenging due to its poor sinteractive nature. The acceleration of shrinkage behavior, improved sinterability and larger grain size were achieved by the partial substitution of Zr with Ni in the BZY perovskite. Phase pure Ni-doped BZY powders of nominal compositions BaZr_0.8-xY_0.2Ni_xO_3-δ were synthesized up to x = 0.04 using a wet chemical combustion synthesis route. BaZr_0.76Y_0.2Ni_0.04O_3-δ (BZYNi₀₄) exhibited adequate total conductivity and the open circuit voltage (OCV) values measured on the BZYNi₀₄ pellet suggested lack of significant electronic contribution. The improved sinterability of BZYNi₀₄ assisted the ease in film fabrication and this coupled with the application of an anode functional layer and a suitable cathode, PrBaCo₂O_5+δ (PBCO), resulted in a superior fuel cell power performance. With humidified hydrogen and static air as the fuel and oxidant, respectively, a peak power density value of 428 and 240 mW cm^-2 was obtained at 700 and 600°C, respectively.