Superior Active and Durable Air Electrode for Protonic Ceramic Cells by Metal-Oxide Bond Engineering.

Protonic ceramic cells (PCCs) have been identified as promising energy conversion devices, offering flexible fuel options and reduced operating consumption at intermediate temperatures. However, the application of traditional cobalt-based perovskite air electrodes in PCCs is hindered by their insufficient durability and high coefficient of thermal expansion. In this study, a straightforward metal-oxygen bond engineering is conducted, introducing a single-phase perovskite, BaLa(FeZn)NO (BLFZN0.1), as a substitution for cobalt-based perovskite. BLFZN0.1 demonstrates superior electrochemical properties, with an area-specific resistance of 0.015 Ω cm at 700 °C, and demonstrates reliable durability over 100 h. The introduction of Ni element increases the concentration of oxygen defects and enhances the oxygen catalytic activity. As a result, a protonic ceramic fuel cell using BLFZN0.1 air electrode achieves the highest peak power density (1353 mW cm⁻ at 700 °C) yet recorded for cells with BLFZ-based air electrodes. Furthermore, the single cell with BLFZN0.1 exhibits remarkable current density (1.66 A cm at 700 °C) in the electrolysis mode, highlighting its potential for application in electrolysis devices. This study presents an effective and straightforward strategy for modifying PCC air electrodes with high electrochemical performance and comparable durability, thereby facilitating their commercial application.