A‐Site High‐Entropy Perovskite Enabling Sulfur‐Tolerant and Coking‐Resistant Anodes for Hydrocarbon‐Fueled Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are capable of electrochemically converting fossil fuels such as natural gas and coal‐based syngas directly into electricity with high efficiency and minimal emissions, yet the state‐of‐the‐art nickel‐based anodes are susceptible to sulfur poisoning or coking when operated with sulfur‐containing or hydrocarbon fuels. Here, we report a high‐entropy strategy in which five equimolar cations are introduced at the A‐site to develop a highly active and robust perovskite anode, Pr 0.2 Ba 0.2 La 0.2 Sr 0.2 Ca 0.2 FeO 3‐δ (PBLSCF). In situ reduction of PBLSCF leads to the exsolution of nanoscale Fe particles, enhancing its tolerance to sulfur poisoning and coking. Electrolyte‐supported single cells using PBLSCF anodes achieve a peak power density (PPD) of 1.22 W cm −2 at 800°C in H 2 , maintain stable operation for 1000 h and exhibit promising sulfur tolerance in 50 ppm H 2 S‐H 2 . Density functional theory (DFT) calculations reveal that the high‐entropy strategy reduces oxygen‐vacancy formation energy, contributing to improved sulfur tolerance and fuel oxidation performance. Furthermore, stable operation using a PBLSCF anode for 600 h is also achieved with propane as fuel. This work provides a synergistic strategy through A‐site high‐entropy engineering and in situ metal exsolution to achieve promising electrochemical performance and enhanced multi‐tolerance anodes for fuel‐flexible SOFCs.