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+δ with 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+δ as the cathode was 0.041 Ω·cm2 at 800 °C and 0.118 Ω·cm2 lower than that of the symmetrical cell with Pr0.5Ba0.5CoO3+δ as the cathode, indicating that the Pr0.5Ba0.5Co1-XNiXO3+δ cathode material has 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+δ cathode material effectively reduced, resulting in improved matching between the cathode and electrolyte material. The power density of the single cell increased by 69 mW/cm2. Therefore, Pr0.5Ba0.5Co1-XNiXO3+δ is a promising candidate cathode material for high-performance SOFCs.