Enhancement of oxygen reduction reaction through coating a nano-web-structured La0.6Sr0.4Co0.2Fe0.8O3-δ thin-film as a cathode/electrolyte interfacial layer for lowering the operating temperature of solid oxide fuel cells

Lowering operation temperature of the solid oxide fuel cell is critical to improving its reliability and durability. However, the tradeoff between the operation temperature and the oxygen reduction reaction on the cathode side hinders lowering of the operation temperature. To address this issue, we employ a nano-web-structured La0.6Sr0.4Co0.2Fe0.8O3-δ (NW-LSCF) thin-film layer as an interlayer on the cathode side. This thin-film layer enables operating the cell at a low temperature with enhancement of the electrochemical performance by increasing the oxygen-reduction reaction site and is fabricated via a simple spin-coating method. The large surface area of NW-LSCF enables significant improvement in the oxygen reduction reaction by an increased triple-phase boundary. In addition, the adhesion property between the gadolinium-doped ceria electrolyte and cathode is improved by the layer. In an anode-support-type single cell test, the peak power density of the cell with NW-LSCF is 0.57 W/cm2 at 550 °C, which is an approximately 63% improvement compared to that of the cell without NW-LSCF. Moreover, the value is comparable to the peak power density of the cell without NW-LSCF operating at 600 °C. This finding suggests the possibility of lowering the operating temperature of the solid oxide fuel cell by introducing NW-LSCF into the cell.