Nanoscaled Sm-doped CeO₂ buffer layers for intermediate- temperature solid oxide fuel cells

A dense and crack-free nanoscaled Sm-doped CeO₂ (SDC) thin film as a buffer layer for intermediate-temperature solid oxide fuel cells has been successfully deposited onto the polycrystalline yttria-stabilized zirconia (YSZ) electrolyte by pulsed laser deposition (PLD). SEM and XRD results reveal that the dense and crack-free buffer layer effectively prevents the formation of the insulating layer between the Ba_0.5Sr_0.5Co _0.8Fe_0.2O_{3 - δ} (BSCF) cathode and the YSZ electrolyte. The fuel cell with the as-deposited buffer layer exhibits high peak power density (e.g., 2016 mW cm^{- 2} at 700 C) and low resistance. In contrast, at 700 C the fuel cell with an optimized SDC layer prepared by spray deposition or the fuel cell without interlayer have lower peak power densities, 1132 mW cm^{- 2} and 60 mW cm^{- 2} respectively, and higher resistances. The significant enhancement in peak power densities with the adoption of the SDC buffer layer by PLD is likely due to the combination of three factors: the lack of solid-state reaction between BSCF and YSZ, the thinner thickness in comparison to the SDC layer by spray deposition, as well as the improvement of the charge-transfer process.