Composite electrolyte with Ruddlesden-Popper structure Sm1.2Sr0.8Ni0.6Fe0.4O4+δ for high-performance low temperature solid oxide fuel cells

Ruddlesden-Popper (R–P) structure oxide has been widely used as the electrode material in low temperature solid oxide fuel cells (LT-SOFCs) because of its high catalytic activity and excellent oxygen transport performance, while the studies on this material served as the electrolyte of LT-SOFCs is rarely reported. Herein, the R–P P-type semiconductor Sm1.2Sr0·8Ni0·6Fe0·4O4+δ (SSNF) oxide material was prepared and then used as electrolyte by constructing P–N heterostructure with the N-type semiconductor Sm0.075Nd0.075Ce0·85O2-δ (SNDC) oxide material. Experimental results showed that the developed 5SSNF-5SNDC composite electrolyte exhibited a high ionic conductivity of 0.201 S·cm−1 along with remarkable fuel cell power density of 1056 mW·cm−2 at 550·°C. The constructed P–N heterostructure helps to improve the oxygen ion conductivity and thus the electrochemical properties. These results demonstrate that P–N heterojunctions constructed from oxide materials with highly catalytically active R–P structures exhibit excellent electrolyte performance. This work provides a new perspective for developing advanced electrolytes of LT-SOFCs.