OPTIMISATION OF THE CATHODE COMPOSITION FOR THE INTERMEDIATE TEMPERATURE SOFC

Electrochemical characteristics of various half-cells have been investigated to optimize the composition of cathodes for intermediate temperature solid oxide fuel cells (SOFCs). The objective of this study is to analyze the performance of half-cells Ce0.8Gd0.2O3 | La0.6Sr0.4CoO3, Ce0.8Gd0.2O3 | Pr0.6Sr0.4CoO3, and Ce0.9Gd0.1O3 | Gd0.6Sr0.4CoO3 using electrochemical impedance, cyclic voltammetry, and chronoamperometry. The experiments were conducted at various electrode potentials and temperatures, revealing that lower temperatures are characterized by kinetic limitations and mass transfer resistance within the cathode structure. Results indicated that the total polarization resistance ranked Sys 1 < Sys 2 < Sys 3, corresponding to the increasing atomic mass of A-site cations in the perovskite framework. The activation energy decreased with more negative polarization in the order Sys 3 > Sys 2 > Sys 1, and the transfer coefficient for oxygen reduction suggests a transition from charge transfer to mass transport limitations at lower temperatures. The electrochemical behavior for half-cells Sys 2 and Sys 1 was consistent over long testing periods exceeding 1200 hours.