Scalable and facile fabrication of tri-layer electrolytes by reactive sputtering for efficient and durable solid oxide fuel cells

Scalable and facile fabrication of large-area electrolytes by physical vapor deposition (PVD) for efficient and durable solid oxide fuel cells (SOFCs) is a promising way to tackle the issues such as elemental diffusion and warpage of cells resulted from high-temperature sintering in conventional wet ceramic methods. Herein, high-performance industrial size, 12 × 12 cm², electrolytes are successfully fabricated by reactive sputtering on commercially obtained nickel oxide-yttria-stabilized zirconia (NiO-YSZ) anode without any pretreatment. Electrolytes of 6-μm-thick with gadolinium-doped ceria (GDC)|YSZ|GDC tri-layer configuration are fabricated with less than 2.5-h sputtering and followed by annealing at 1000 °C, much lower than that adopted in traditional wet process. In combination with traditional La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) cathodes, SOFCs with sputtered electrolytes show open circuit voltages close to the theoretical values, excellent electrochemical performances and long-term stability. The initial peak power densities of such cells reach 1.80, 1.24, 0.75 and 0.42 W cm⁻² at 800, 750, 700 and 650 °C, respectively. The performance increases slightly in the initial stage and then stabilizes without degradation during the 300-h stability test under a constant voltage of 0.8 V at 650 °C. The scaled-up deposition area and the high deposition rate (∼2.5 μm h⁻¹) show promising opportunities in the mass production of SOFCs using reactive sputtering.