Effect of the thickness of sputtered gadolinia-doped ceria as a cathodic interlayer in solid oxide fuel cells

•Gadolinia-doped ceria was used as a cathodic interlayer in solid oxide fuel cells.•Sputter was used to deposit gadolinia-doped ceria.•Gadolinia-doped ceria interlayer improved the electrochemical performance.•100 nm or thicker gadolinia-doped ceria showed a full functionality as interlayer.

Sputtered gadolinia-doped ceria (GDC) film was introduced as the cathodic interlayer between an yttria-stabilized zirconia (YSZ) pellet and a Pt cathode in solid oxide fuel cells (SOFCs). The fuel cells with none, 50, 100 and 150 nm thick GDC interlayers were fabricated to investigate the effect of the thickness of the GDC interlayer. The performances of the SOFCs with the 100 and 150 nm thick GDC interlayers operated at 450 °C showed the highest performance. Through electrochemical impedance analysis, it was visualized that the GDC interlayer significantly reduced the faradaic resistance of the SOFC. The degradation of the performance from the increased ohmic resistance by adding the GDC interlayer was negligible. From the topographical images scanned by atomic force microscope, it was observed that the 50 nm thick GDC interlayer did not perfectly cover the surface of the YSZ pellet, resulting in incomplete performance enhancement by the sputtered GDC.