Oxygen Exchange in MIEC Perovskite Oxide La0.6Sr0.4Co0.2Fe0.8O3−δ: Kinetic and Equilibrium Parameters and Their Interrelation

This paper is devoted to a detailed study of the kinetic and thermodynamic characteristics of one of the most well-known solid oxide fuel cells cathode materials, La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) oxide, using the original oxygen partial pressure relaxation (OPPR) with macrokinetic model Tanks-in-Series (TIS) and quasi-equilibrium oxygen release (QEOR) techniques. Power-law dependences of kinetic characteristics on the partial pressure of oxygen and their Arrhenius dependences are shown. The equilibrium properties of the oxide are represented as continuous diagrams ⟨⟨T – pO2 – δ⟩⟩ and ⟨⟨T – μO2oxide – δ⟩⟩. It is shown that the Brønsted–Evans–Polanyi homological approach is valid for LSCF and allows us to consider it as a series of δ-homologues involved in the same reaction with gaseous oxygen. The contribution of the entropy factor to the Gibbs activation energy is shown to be superior, which is typical for ferrites of ABO3−δ composition.