Effect of a-Site Cation Defect on Electrochemical Performance and Stability of La0.8Sr0.2Co0.2Fe0.8O3- δ Cathode

The application of Solid oxide fuel cells (SOFCs) is restricted by the insufficient catalytic activity in oxygen reduction reaction and the impedance increase of cathode in long-term operation at medium and low temperature[1]. In this work, we prepare La 0.8 Sr 0.2 Co 0.2 Fe 0.8 O 3- δ (LSCF) nanofiber cathode material with different A-site defects by electrospinning technique, and systematically explore the influence of A-site cation defect on the electrochemical performance and long-term stability of LSCF cathode. The experimental results show that the cathode with La defects at A-site (La 0.77 Sr 0.2 Co 0.2 Fe 0.8 O 3- δ ) obtains better electrochemical performance than the cathode with Sr defects (La 0.8 Sr 0.17 Co 0.2 Fe 0.8 O 3- δ ). With the increase of the proportion of La deficiency at A-site, the long-term operation stability of LSCF cathode is improved, and Sr surface segregation is suppressed. However, excessive A-site deficiency cause lattice instability of LSCF, resulting in the separation of Co 3 O 4 , which reduces the electrochemical catalytic activity of LSCF cathode. Proper A-site defects can not only increase the oxygen vacancy of LSCF material, but also inhibit the Sr surface segregation, which makes La 0.77 Sr 0.2 Co 0.2 Fe 0.8 O 3- δ a promising optimized SOFCs cathode material. Figure 1