Reversible Fe exsolution enables a single-layer Sr2Fe1.5Mo0.5O6−δ ceramic interconnect for plasma-sprayed segmented-in-series solid oxide fuel cells

Double-perovskite Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) is promising for solid oxide fuel cell (SOFC) electrodes due to good redox stability and high conductivity, yet its performance suffers from phase degradation under strong reduction. Herein, SFM coatings were prepared via atmospheric plasma spray (APS) to investigate phase and valence evolution under redox cycling. The exsolved metallic species can reversibly re-incorporate back into the perovskite lattice upon re-oxidation. The material maintains conductivity above 10 S cm −1 during repeated redox cycles. SFM was further applied as standalone interconnect in plasma-sprayed segmented-in-series tubular SOFCs. A 15-cell stack with SFM interconnect delivers peak power of 19.0 W (0.39 W cm −2 ). This work validates SFM as a viable perovskite interconnect and offers new insights for high-temperature dual-atmosphere ceramic material design.