Electrochemical behavior of La_0.8Sr_0.2FeO₃ electrode with different porosities under cathodic and anodic polarization

Electrochemical behavior of La_0.8Sr_0.2FeO₃ (LSF) electrode with different porosities under cathodic and anodic current polarization has been investigated by electrochemical impedance spectroscopy and the galvanostatic method. The activation and degradation behavior of the LSF electrode may be related to the partial reduction and oxidation of the Fe ions under cathodic and anodic polarization, especially in the LSF electrodes with high porosities. The performance of the LSF electrode has been found to depend on the oxygen vacancies at the LSF surface, which would promote the transport of oxygen intermediate species at the LSF surface close to the triple-phase boundary (TPB) region. Results show that the polarization resistance (Rp) of the LSF electrode decreases at the beginning with the increase of cathodic polarization time, while Rp always increases with the increase of anodic polarization time. The effect of cathodic and anodic polarization becomes predominant with the increasing of the porosities of the LSF electrode, which is ascribed to the decrease of the interface area between electrode and electrolyte.