A-site cation deficiency tuned oxygen transport dynamics of perovskite Pr0.5Ba0.25-xCa0.25CoO3-δ oxide for intermediate temperature solid oxide fuel cells

Perovskite oxides with ionic and electronic conductivity are the key cathode materials of solid oxide fuel cells. Most of these materials, however, exhibit large cathodic polarization resistance which is mainly determined by their tardy oxygen transport kinetics. Herein, Pr0.5Ba0.25-xCa0.25CoO3-δ is studied to understand the roles of Ba-deficiency in tuning oxygen transport and electrochemical behaviors in the system. Our findings indicate that Ba-deficiency can significantly accelerate oxygen surface exchange process and bring ∼77% reduction of polarization resistance in this process. It is interesting to note that Ba-deficiency can slightly slow oxygen ion bulk diffusion rate and induce a minor increase of polarization resistance in the corresponding process, which associates with the inhibited oxygen vacancy mobility caused by the interactions between negatively charged Ba vacancy and positively charged oxygen vacancy. These new findings pave a new path for solid oxide fuel cell design and chemical sensor developments.