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

• An extremely thin dense buffer layer is fabricated by PLD.
• The peak power density is significantly improved to 2016 mW cm− 2 at 700 °C.
• The interfacial reaction is suppressed by inserting a nanoscaled buffer layer.
• Thin films improve the charge-transfer process at the interface.

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 Ba0.5Sr0.5Co0.8Fe0.2O3 − 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.