Decoupling analysis for advanced electrochemical ceramic oxygen pumps

Ceramic oxygen pumps (COPs) have demonstrated significant advantages in continuous high-purity oxygen production by integrating electrochemical reactions and separation within oxygen-permeable membrane reactors. However, their industrial application remains constrained by the lack of highly active electrodes at temperatures below 750 °C. In this study, we developed a three-electrode structure to decouple the electrodes for analyzing the performance evolution of the COPs under different atmospheric conditions. Through rigorous in situ decoupling tests of diverse electrodes, a comprehensive analysis of impedance data revealed that the resistance of the oxygen evolution reaction (OER) process in pure oxygen is predominantly attributed to the ion diffusion process of the electrode. Meanwhile, the resistance of the oxygen reduction reaction (ORR) on the air side is attributable to both the surface gas absorption and bulk ion transport processes. Furthermore, an electrolyte (200 μm) supported COPs was constructed using the preferred cathode Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ and anode SrCo_0.8Nb_0.1Ta_0.1O_3-δ. This COP achieves a high current density of 1956 mA cm⁻²@0.6 V at 750 °C and maintained excellent operating stability over 144 h.