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A high-performance solid oxide fuel cell (SOFC) stack technology is being developed, based on a design concept that incorporates prime-surface metallic interconnects with the versatility of stacking different types of single cells (sintered cells or metal-supported cells). A preliminary design of the prime-surface interconnect based on an egg-carton shape configuration has been advanced for this stack concept. Laboratory-scale prime-surface interconnects have successfully been fabricated by stamping and evaluated for mechanical loading, flow distribution and current collection properties. A process based on sputtering has been developed for fabricating supported thin-film (several micrometers thick) cells for this stack technology. Fabricated thin-film cells have shown desirable structural characteristics and exceptional performance on different fuels at reduced temperatures (550o-650oC). Sputtered cells (with yttria stabilized zirconia (YSZ) for the electrolyte, gadolinia-doped ceria (GDC) for the electrolyte/cathode interlayer, nickel-YSZ for the anode and lanthanum strontium cobalt iron perovskite (LSCF)–YSZ for the cathode) have exhibited peak power densities of ~1.7 W/cm2 and ~2.1 W/cm2 with hydrogen fuel and air at operating temperatures of 600oC and 650oC, respectively.

A process based on sputtering has been developed for fabricating thin-film solid oxide fuel cells (TF-SOFCs) that have a total thickness of ~3 µm and are based on the conventional configuration using common SOFC materials. Single cells (with dense electrolytes, dense interlayers, and porous electrode films) on various substrates were effectively fabricated through sputtering/co-sputtering of metal and/or ceramic targets and the electrodes exhibited a fine nanostructure consisting of very small columns of roughly 10 nm in diameter. Fabricated cells exhibit open circuit voltages of ~1.0 V and exceptional power densities at reduced temperatures (500o-650oC) on different fuels. Single cells (of the composition lanthanum strontium cobaltite-gadolinium doped ceria (LSC-GDC) cathode/GDC interlayer/yttria stabilized zirconia (YSZ) electrolyte/Ni-GDC anode) show record power densities of ~3.5 W/cm2 with hydrogen/air and ~1.5 W/cm2 with dry methane/air at 650oC.