A bi-layer cathode based on lanthanum based cobalt- and iron-containing perovskite and gadolinium doped ceria for thin yttria stabilized zirconia electrolyte solid oxide fuel cells

Composite cathodes based on La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) are investigated for lower operating temperature (<750 °C) applications of a solid oxide fuel cell (SOFC). To enhance a charge transfer, a bi-layer SOFC cathode is proposed, which has a LSCF–Ce0.9Gd0.1O1.95 (GDC) composite layer and a pure LSCF layer. The bi-layer cathode SOFC shows a current density of 0.65 A cm−2 at 0.8 V and 660 °C, which is higher than a LSCF–GDC composite single-layer cathode SOFC cell of 0.35 A cm−2. The charge transfer polarizations in the bi-layer cathode SOFC are 0.14 Ω cm2 and 0.35 Ω cm2 at 760 °C and 660 °C, respectively, which are lower than those in the single-layer cathode cell of 0.23 Ω cm2 and 0.66 Ω cm2. The impedances characterized with a fitting model show that the lowered charge transfer polarization in the bi-layer cathode is a dominant factor in reducing the total polarization of SOFC.