MgO-MgAl ₂ O ₄ -Supported Flat-Tubular Segmented-In-Series SOFCs Featuring Ultra-High Conductivity Interlayer for Enhanced Performance

Development of a highly conductive interlayer with good multilayer interfacial compatibility is critical for achieving high-performance inert ceramic-supported flat-tubular segmented-in-series solid oxide fuel cells (FT-SIS-SOFCs). In this study, a high-performance MgO-MgAl 2 O 4 (MMA)-supported solid oxide fuel cell is prepared by developing an innovative 70 vol % NiO-30 vol % MgAl 2 O 4 interlayer via a cosintering process. The NiO-MgAl 2 O 4 interlayer effectively suppresses MgO diffusion from the MMA substrate, limiting the diffusion distance to 25 μm. Additionally, the conductivity of the fabricated interlayer exceeds 3400 S cm –1 at the operational temperature. It exhibits excellent cosintering compatibility with the other functional layers. When the thickness of the NiO-MgAl 2 O 4 interlayer is approximately 40 μm, the MMA-supported SOFC single cell shows an open circuit voltage (OCV) of about 1.07 V and a power density of 760 mW cm –2 at 850 °C, as well as excellent long-term stability. Moreover, the 16-cell FT-SIS-SOFCs show an OCV and maximum output power at 850 °C of 17 V and 15 W, respectively.