A novel CO2-tolerant Ba0.5Sr0.5Co0.8Fe0.1Ta0.1O3-δ cathode with high performance for proton-conducting solid oxide fuel cells.

The application of traditional MIEC cathode material Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) in the solid oxide fuel cell (SOFC) field is limited due to its susceptibility to CO 2 and high thermal expansion coefficient. Therefore, improving the stability of BSCF cathode in CO 2 -containing environments and the matching degree between BSCF and electrolyte are the key factors to achieve its excellent electrochemical and stable performance for intermediate temperature solid oxide fuel cells (IT-SOFCs). Herein, the cathode materials Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2-x Ta x O 3-δ (X = 0, 0.1, 0.2) are successfully prepared and the effects of Ta-doped content are investigated systematically. With the increase of Ta-doped content, the thermal expansion coefficient of BSCF 0.2-x T x decreases from 25.1 × 10−6 K−1 to 16.5 × 10−6 K−1, which indicated that Ta-doped enhanced the combination of cathode material and electrolyte. In single-cell applications, the maximum power density of 926.4 mW cm−2 and the lowest polarization resistance of 0.06 Ω cm2 at 700 °C are achieved. Furthermore, theoretical calculations show that the CO 2 adsorption energy of BSCFT is 0.12 eV higher than that of BSCF, indicating that BSCFT exhibited improved resistance to CO 2 corrosion compared with BSCF. It is indicated that the Ta-doping strategy has the advantage of improving both the performance and stability of BSCF cathode materials. • BSCF cathode materials doped with different concentrations of Ta were prepared. • The good stability of Ta-doped BSCF cathode materials were confirmed. • The effect of Ta doping on CO 2 resistance was analyzed by theoretical calculations. • BSCF 0.1 T 0.1 material achieved excellent fuel cell performance with good stability. [ABSTRACT FROM AUTHOR]