Lattice strain-engineered heterointerface in Ce3+-doped Pr0.6Sr0.4Co0.2Fe0.8O3-δ composite cathodes for IT-SOFCs

Constructing beneficial heterostructured interfaces in cathode materials represents an effective strategy for enhancing cathodic oxygen reduction reaction kinetics in intermediate-temperature solid oxide fuel cells (IT-SOFC). Herein, a novel heterostructured nanocomposites Pr 0.5 Ce 0.1 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -CeO 2 (PCSCF-C1) was designed by substituting partial Pr 3+ (1.013 Å) with larger Ce 3+ (1.34 Å) ions, coupled with a redox-induced phase transformation (Ce 3+ →Ce 4+ ). Specially, the in situ -engineered heterointerface introduces a 1.15% lattice tensile strain, which weakens the B-O bonding energy, increases oxygen vacancy concentration, and accelerates the surface oxygen exchange rate through synergistic effects. As a result, the PCSCF-C1 cathode exhibits a low polarization resistance ( R p ) of 0.020 Ω·cm 2 at 800 °C in LSGM-based symmetric cells, together with improved CO 2 tolerance. When integrated into an anode-supported single cell, it delivers a maximum peak power density of 2.29 W·cm −2 at 800 °C and maintains stable operation over 248 h at 750 °C. This work demonstrates a lattice strain-engineered heterostructure design for advancing high-performance IT-SOFC cathodes.