Realizing B-site high-entropy air electrode for superior reversible solid oxide cells

The operational efficiency of reversible solid oxide cells (R-SOCs) is hindered by the limited electroactivity and longevity of air electrodes. High-entropy engineering at the B site can reduce the Co content, enhance the compatibility of air electrodes and electrolyte thermal expansion coefficients, and introduce synergistic effects of multi-elements. In this pioneering work, we successfully prepared a single-phase air electrode, PrBa0.8Ca0.2Fe0.4Co0.4Ni0.4Cu0.4Zn0.4O6-δ (HE-PBC-FCNCZ). The cell with HE-PBC-FCNCZ as the air electrode exhibits a peak power density of 1.42 W cm−2 in fuel cell (FC) mode at 700 ℃, demonstrating robust stability. Its remarkable electrochemical performance and stability rank among the top tier of perovskite cathode materials. X-ray absorption near edge structure (XANES) analyses indicated minimal changes in the oxygen content after the stability test compared to PBCC. This study introduces novel B-site high-entropy air electrodes for R-SOCs, featuring both elevated activity and extended durability.