Processing of Lanthanum-doped Strontium Titanate Anode Supports in Tubular, Solid-Oxide Fuel Cells

摘要

This work focuses on ceramic-processing techniques for fabrication of tubular solid-oxide fuel cells (SOFCs) based on perovskite anode supports. Two types of SOFCs are fabricated; both utilize a Sr_(0.8)La_(0.2)TiO3 / Y_(0.08)Zr_(0.92)O2 (SLT-YSZ) anode support, a YSZ electrolyte and an (La_(0.8)Sr_(0.2))_(0.98)Mn_(O3-x) - YSZ (LSM-YSZ) cathode. Once cell includes no additional catalyst, and the second cell utilizes a thin Ni-YSZ anode-functional layer (AFL) at the interface between the SLT-YSZ support and the YSZ electrolyte. The NiO present in the anode functional layer is found to act as a sintering aid to the SLT support. This causes rapid densification in the support near the NiO/anode-support interface, and internal stress that cause cell fracture during sintering. This localized sintering is alleviated through addition of a diffusion barrier layer between the SLT-YSZ support and the Ni-YSZ anode functional layer. The barrier layer is comprised of Ga_(0.1)Ce_(0.9)O2 (GDC) and YSZ, resulting in a five-layer membrane-electrode assembly. Stability of these two materials sets throughout the high-temperature fabrication processes is confirmed using x-ray diffraction, dynamic shrinkage dilatometry, and electron microscopy. Cell performance is measured under humidified hydrogen at 800 °C; results are used to infer the effectiveness of the added catalyst, and the viability of perovskite anode supports in tubular SOFC architectures.