Self‐Assembled Perovskite Nanocomposite With Beneficial Lattice Tensile Strain as High Active and Durable Cathode for Low Temperature Solid Oxide Fuel Cell

Abstract The sluggish kinetics of oxygen reduction reaction (ORR) at low temperatures and the fast degradation of the cathode are the main obstacles to the commercialization of solid oxide fuel cells (SOFCs). However, it is still very challenging to achieve both high catalytic activity and favorable stability for single‐phase materials. Herein, a highly active and durable nanocomposite cathode (Ba 0.5 Sr 0.5 ) 0.75 Pr 0.25 Co 0.575 Fe 0.3 W 0.125 O 3‐δ (BSPCFW) for low‐temperature SOFC (≤650 °C) is presented, which self‐assembles into two cubic perovskites: the simple perovskite Pr 0.38 Ba 0.25 Sr 0.37 Co 0.62 Fe 0.38 O 3‐δ (PBSCF‐ c ) and the B‐site cations ordered double perovskite Ba 1.30 Sr 0.70 Co 1.0 Fe 0.25 W 0.75 O 6‐δ (BSCFW‐ c ). The former PBSCF‐ c serves as the highly conductive and active catalyst for ORR, while the latter BSCFW‐ c with a large lattice parameter introduces a key beneficial lattice tensile strain into the PBSCF‐ c phase through a coherent interface, which significantly promotes the ORR activity at low temperatures with the area specific resistance of 0.034 Ω cm 2 at 650 °C, and the long‐term stability of 2 years storage and 1280 h operation in symmetrical cell. The introduction of the beneficial lattice tensile strain in self‐assembled composite catalysts is an effective way to synergistically enhance the electrochemical activity and durability of the electrode materials for electrochemical devices.