Anomalous low-temperature sintering of a solid electrolyte thin film of tailor-made nanocrystals on a porous cathode support for low-temperature solid oxide fuel cells

High Ohmic resistance of the solid electrolyte film is a critical issue of low-temperature solid oxide fuel cells (SOFCs) that needs to be addressed. In this study, tailored ceramic Gd-doped ceria (GDC) nanocubes with highly reactive {100} facets were densely integrated on a low-temperature-sinterable (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) cathode support by electrophoretic deposition (EPD). The densely packed GDC nanocube thin film was co-sintered with the cathode support at a significantly lower temperature of 1000 °C, which is 300 °C lower than that required for conventional GDC nanoparticles. The well-sintered dense GDC solid electrolyte thin film formed a 1 μm thick layer on the porous cathode support. The anomalous low-temperature sintering was achieved owing to the good sinterability of the GDC nanocubes, their high-density integration on the LSCF support by EPD, and a remarkable shrinkage of the LSCF support. The deposition of a porous cathode functional layer (CFL) with fine carbon nanoparticles as a pore-forming agent yielded a flat surface. The CFL enabled the integration of GDC nanocubes densely on the LSCF cathode support and remained as a preferable contact interlayer. The GDC nanocube-integrated LSCF cathode support fabricated in this work can be a suitable material for low-temperature solid oxide fuel cells.