Sintered powder-base cathode over vacuum-deposited thin-film electrolyte of low-temperature solid oxide fuel cell: Performance and stability

Abstract

To expand the processing options for low-temperature-operating solid oxide fuel cells (LT-SOFCs), the hybridization of powder processing and vacuum deposition is attempted. Nanostructured nickel-yttria-stabilized zirconia (Ni-YSZ) anode functional layer (AFL) and YSZ/gadolinia-doped ceria (GDC) bi-layer electrolyte are fabricated over a sintered anode support by pulsed laser deposition (PLD), a physical vapor deposition technology. The most common powder-processed (screen-printed and sintered) La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.1Ce0.9O1.95 (LSCF-GDC) composite cathode is applied over vacuum-deposited thin-film components. When LSCF-GDC is sintered at a general sintering temperature of 1050 °C then the continuity of the GDC buffer is lost and excessive interdiffusion between the cathode and the electrolyte has occurred at the interface. On the other hand, if the sintering temperature is lowered to 950 °C, peak power density more than 1.7 W cm−2 at 650 °C is obtained. Moreover, the operation stability of the hybrid SOFC (degradation rate ∼8%/100 h) is superior to that of the SOFC with a vacuum-processed nanostructure cathode (degradation rate ∼21%/100 h) when exposed to 0.7 A cm−2 at 650 °C, which is a significantly harsh degradation test condition for LT-SOFCs.