Facile co-synthesis and utilization of ultrafine and highly active PrBa0.8Ca0.2Co2O5+δ-Gd0.2Ce0.8O1.9 composite cathodes for solid oxide fuel cells

Addition of doped ceria to double perovskite oxide such as PrBa0.8Ca0.2Co2O5+δ (PBCC) leads to remarkable performance enhancement of solid oxide fuel cells (SOFCs), however, the challenge is to facilely fabricate nano-structured PBCC cathodes with nanoscale doped ceria without agglomeration of the ultrafine phase during the conventional high temperature electrode sintering process. Here, we report the fabrication of an ultrafine PBCC-Gd0.2Ce0.8O1.9 (GDC) composite via a facile co-synthesis route and direct assembly approach without the high temperature sintering process. The as-fabricated PBCC-GDC composite powder calcined at 750 °C contains PBCC, GDC, BaCoO3-δ (BCO) and PrCoO3-δ (PCO), and only PBCC and GDC phases as the calcination temperature increases to 850 °C and higher. A single cell with the directly assembled multi-phased PBCC-GDC powder calcined at 750 °C exhibits a peak power density of 2.08 W cm−2 at an operating temperature of 750 °C, and is stable at 0.5 A cm−2 and 700 °C for over 100 h. The outstanding electrode performance and stability is primarily ascribed to the in situ formation of intimate electrode/electrolyte interface by polarization and the construction and retaining of ultrafine electrode microstructure. This work shed lights onto the development of a facile strategy to prepare highly active and stable double perovskite based composite cathode for SOFCs.