Layered SmBaCuCoO_5+δ and SmBaCuFeO_5+δ perovskite oxides as cathode materials for proton-conducting SOFCs

A dense BaCe_0.8Sm_0.2O_5+δ (BCS) electrolyte was fabricated on a porous anode by in situ drop-coating to develop a simple and cost-effective route to fabricate proton-conducting solid oxide fuel cells (SOFCs). Layered perovskite-structure oxides SmBaCuCoO_5+δ (SBCC) and SmBaCuFeO_5+δ (SBCF) were prepared and the electrical conductivity, the thermal expansion coefficient and electrochemical performance were investigated as potential cathode materials for proton-conducting SOFCs. Thermal expansion coefficients of SBCC and SBCF were suitable for BCS electrolyte and the electrical conductivity of the SBCC is higher than that of the SBCF. The maximum power density of 449 mW cm² and 333 mW cm² at 700 °C were obtained for the SBCC/BCS/NiO-BCS and SBCF/BCS/NiO-BCS cells, respectively. The interfacial polarization resistances for SBCC and SBCF cathode are as low as 0.137 Ω cm^-2 and 0.196 Ω cm^-2 at 700 °C, respectively. The results indicate that the SBCC and SBCF are promising cathode materials for proton-conducting SOFCs.