Ni-Doped Pr0.5Ba0.5CoO3+δ Perovskite with Low Polarization Resistance and Thermal Expansivity as a Cathode Material for Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) have become promising devices for converting chemical energy into electrical energy. Altering the microstructure of cathode materials to enhance the activity and stability of the oxygen reduction reaction is particularly important. Herein, Pr0.5Ba0.5Co1−XNiXO3+δwith a tetragonal perovskite structure was synthesized through the sol–gel method. The polarization resistance of the symmetrical half-cell with Pr0.5Ba0.5Co0.9Ni0.1O3+δas the cathode was 0.041 Ω·cm2at 800 °C and 0.118 Ω·cm2lower than that of the symmetrical cell with Pr0.5Ba0.5CoO3+δas the cathode, indicating that the Pr0.5Ba0.5Co1−XNiXO3+δcathode material had high catalytic activity during the electrochemical reaction. The results of electron paramagnetic resonance revealed that the concentration of oxygen vacancies increased as the Ni doping amount increased to 0.15. As a result of the increase in the Ni doping amount, the thermal expansion coefficient of the Pr0.5Ba0.5CoO3+δcathode material was effectively reduced, resulting in improved matching between the cathode and electrolyte material. The power density of the single cell increased by 69 mW·cm−2. Therefore, Pr0.5Ba0.5Co1−XNiXO3+δis a promising candidate cathode material for high-performance SOFCs.